The Hogwarts Express, or In Search of . . . Platform Nine and Three-Quarters 

A number of questions are often asked about the Hogwarts Express—how can it be hidden at King’s Cross so effectively?—why is there always just one compartment left? how can it travel around without being seen?

The Hogwarts Express—Muggle features

Muggles, it is suggested in OP7, developed technology because they don’t have magic, so it is unusual for the wizarding world to use such modern muggle inventions as railway trains—although not unheard of: see for example the Knight Bus, or the lifts in the Ministry of Magic. We get quite a full description of the Hogwarts Express from the various books in which it appears. But how magical is it? Let us examine the train in muggle terms—any features which can’t be explained in those terms will, necessarily, be magic.

Most modern passenger trains have no separate locomotive, but have diesel or electric motors mounted under the passenger carriages, and a driver’s cab in the leading carriage. However, we can deduce from the books that the Hogwarts Express is a steam train—that is to say a set of carriages with a separate locomotive. This traditional arrangement was normal for steam trains, and is still used today for freight trains and some passenger trains.

Steam locomotives ceased normal use in Britain in 1968. Although in the 1990s, when the Harry Potter books are set, one would certainly notice a steam train on the main line, it would not raise many muggle suspicions as they are still occasionally used for special charters such as the Orient Express, or for filming purposes, such as the Harry Potter films. Incidentally, the carriages used in the films are a set dating from the 1950s, hauled by former Great Western Railway steam locomotive No. 4972 “Olton Hall”, built in 1938 and named after a minor stately home in Warwickshire. (The fact that there were enough such namesakes for a fleet of 330 “Halls,” as well as 165 of the larger “Castle” class, and 110 of the smaller “Grange” and “Manor” classes, may say something about the English class system!) Painting No. 4972 red for the films shocked many railway preservation purists, as its original GWR colour scheme was dark green!

We also learn very early on in the books that the carriages are of the traditional British compartment layout. For the benefit of non-British readers, and indeed younger British ones, I should explain that until about 1965, most British railway carriages were divided by transverse partitions into several separate compartments, each having two rows of seats facing each other. Long-distance trains had a corridor running along one side of the carriage to allow people to move about the train, and it is apparent from the books that the Hogwarts Express is of this type. (The interior shots of the train in the first film are also of a carriage of this type.) Each carriage had between seven and eleven compartments, and each compartment would seat between six and twelve people, depending on whether there was a corridor and whether it was First or Second Class, but typically there would be eight compartments, each seating eight people at a squeeze.  The very last compartment coaches (apart from sleeping cars) to be built were a handful of First Class carriages built as recently as 1988 for the service from London Waterloo to the Hampshire and Dorset coast, and which were withdrawn from service in early 2007.

Hermione refers a few times to the “prefect carriage” (PS6, OP10, HBP7). Two students from each house are appointed prefect in their fifth year, and presumably normally remain in post for the subsequent two years, so there would normally be 24 prefects in the school at any one time, for whom three or four compartments should be enough accommodation, but as the prefects are supposed to patrol the corridors they do not all need seats at the same time. Indeed Percy (PS6) says that there are only two compartments for the prefects. We also note that in his sixth year (HBP7) Malfoy, who was a prefect in Year 5 (OP10), does not sit with the prefects—unless he has been demoted, he has presumably decided not to mix with the others (most of them are not Slytherins, after all!).

As Harry always seems to have difficulty finding an empty seat, but nevertheless always manages to do so, the number of carriages may be safely said to be “just enough.” But this does not require a magical explanation. Operators of private trains like the Hogwarts Express have an advantage over those open to the public, in that they know in advance how many people are travelling—in this case the entire school, and no-one else. They can therefore provide “just enough” carriages, however many that is. The fact that Harry always finds exactly one compartment can also be explained without magic—firstly, he is usually, for one reason or another, one of the last to join the train so he is going to find most of the seats already taken; but even more prosaically, he stops looking as soon as he finds an empty seat: there may in fact be more empty compartments beyond the one he finds.

So how long is the train? Well, that depends how many students there are at Hogwarts, which has exercised many people’s minds already! In the Quidditch final in Harry’s third year (PA15) there are said to be 300 Slytherin supporters, despite the Hufflepuffs and Ravenclaws all rooting for Gryffindor. If all the houses were about the same size, this would suggest the school has more than a thousand students. But elsewhere in the books, we learn that in Harry’s year there are only five boys in Gryffindor, and that the total number of Slytherins and Gryffindors in Harry’s year is twenty (see the broomstick lesson in PS11). The number of Hufflepuffs in Harry’s year must also be the same as the Slytherins (twenty earmuffs in the mandrake lesson—CS6). But we cannot conclude from this that there are exactly five students of each gender in each house: not even in Harry’s year, let alone any other. Indeed, the form of the sorting ceremony suggests otherwise, because it seems that the Sorting Hat has a completely free choice for each student. If there was a quota, and Harry had been sorted into Slytherin as the hat had intended, by the time it got to Blaise Zabini there would already have been five Slytherin boys (including Harry), but only four Gryffindors. So if there was a quota of five boys per house, the hat would have had no choice but to sort Zabini into Gryffindor!

Even if each year starts with exactly forty students, there will be fewer as you progress further up the school, as we know of several students who failed to complete the course—Moaning Myrtle, Rubeus Hagrid, Cedric Diggory, and the Weasley twins. It may also be the case that, as in British muggle schools, some students leave at age 16, after taking their O.W.L.s. Perhaps Stan Shunpike was one such—he is 21 in HBP11 and therefore only 18 when Harry first meets him on the Knight Bus (PA3): he would surely have recognised Harry if, like Harry, he had spent the previous two years at Hogwarts!

But let us assume forty is a typical intake for one year—this would suggest a student population of about 280, requiring 35 eight-seat compartments (five carriages) or  a more comfortable 47 six-seat compartments (six carriages). However, given that most students seem to take their luggage into the compartments with them, rather than stow it in a separate baggage car, four or five to a compartment might be more practical, requiring between seven and nine carriages. One other point—in OP10 Harry finds “people staring at him in five consecutive carriages,” so there must be at least that many.

Speed

How fast can the Hogwarts Express travel? If it runs on the main line out of King’s Cross station, it needs to keep out of the way of the regular trains on that line. These run several times an hour, and have a cruising speed of 125 mph (hence the name InterCity 125). Could the Hogwarts Express keep up with them? I doubt it—only one steam train has ever been recorded travelling as fast as this. The locomotive in question was No. 4468 “Mallard,” one of a fleet of streamlined locomotives built for the London & North Eastern Railway for services from King’s Cross to north east England and Scotland. It was pulling a special test train, not a scheduled service, and managed this speed for less than a mile, at the end of a long downhill stretch, and suffered a major bearing failure and had to be towed to London for the press call to mark the setting of this record.

That was in 1938, nearly seventy years ago. No other British steam train, before or since, has come within 10% of that speed. (German and American ones have come close, but the dimensions of bridges and tunnels in Britain prevent its locomotives being built as large—and therefore as powerful—as those elsewhere.) If the Hogwarts Express is a steam train capable of running at sustained speeds of 125 mph, it is not any steam train known to muggle technology.

Alternatively, the Hogwarts Express could be running more slowly, and being overtaken by the faster muggle services. This would require the Hogwarts Express to be sidelined several times an hour to allow the fast trains to run through on the main line. This seems very unlikely, if only because, in PA5, just before the Dementor arrives, everyone is surprised that the train is stopping. If the train was stopping every few miles, no-one would remark particularly on there being yet another stop.

It may, like the Knight Bus, be able to jump out of the way of other trains, but another possibility is that the Hogwarts Express takes a less busy route to the north, or at least one where the trains go less fast so that it can keep up—the Midland main line from St Pancras or the Great Central route from Marylebone are possibilities. However, these routes are difficult to reach from King’s Cross. Except . . .

We know that the train is capable of operating in magical space, as the journey starts at the magical platform nine and three-quarters. There are significant clues to suggest that platform nine and three-quarters is not connected to the main line out of King’s Cross, but to some other, perhaps more magical, railway. The clues are what Harry first sees of the Hogwarts Express, and the last thing he sees of the station as it leaves.

Consider how Harry arrives on the platform: the first thing he sees is the locomotive, which is odd because King’s Cross is a terminus. At a terminus, the railway lines come to a dead end, and the entrances to the platforms are reached from a concourse stretching across the ends of the platforms (see diagram). You therefore enter the platform next to the dead end of the track. If there is a locomotive at that end of the train, it has brought the train into the station, but it is certainly not going to be pulling the train any further—another locomotive must be attached to the far end of the train, ready to take it out.

At small country terminus stations (possibly at Hogsmeade), it was common for the locomotive to uncouple, and then use a parallel track to move to the other end of the train and couple up again, but in big city stations there is not the space for extra tracks, and express locomotives also need to be turned round to face the right way, and refuelled, before they are ready for another long journey.

Some trains operate in “push-pull” mode, with the locomotive at the same end of the train all the time—the driver controls it remotely from a cab in the leading carriage when the locomotive is pushing. Many modern trains operate this way, (InterCity 125s have a locomotive at both ends) but using steam technology it was not possible to propel more than two coaches, and speed was severely restricted.

Another possibility is that the driver simply called “Accio Locomotive”, and got it to change ends that way. But surely he would not have allowed hordes of students on to the platform until after he had caused a locomotive weighing 100 tons or more to fly the length of the platform??

Another difficulty at King’s Cross is that we also read (for example in PS6, PA5, GF11, OP10, HBP7) that Harry, looking back as the train pulls away from the station, watches the people standing on the platform until the train turns a corner. But trains leaving from King’s Cross don’t disappear round a bend, they disappear into a tunnel a few coach-lengths from the end of the platform.

It may seem strange that when Harry first sees Molly Weasley (PS6) her children have to remind her where to find the Hogwarts Express, even though she has been sending her children to Hogwarts for nine years already, and she herself also attended Hogwarts (probably not very long before, since she met Arthur when they were both students: HBP5). However, it is likely that, with a young family (four children under five when Bill started!), she stayed at home with the younger ones, whilst Arthur took the older ones to King’s Cross. And when Molly herself went to school, the platforms at King’s Cross were numbered rather haphazardly and there was no platform 3 nor, more significantly for our purposes, platform 9. The platforms were renumbered in 1970, (which is about the latest that Molly could have been to Hogwarts, unless Bill was born whilst she was still at school!), with the original platforms 8, 10, 11 and 12 becoming platforms 7 to 10. I suggest that, in the same way that No. 12 Grimmauld Place is in magical space between Nos. 11 and 13, the absent platform 9 was the original Hogwarts Express platform. The change to the platform numbering, after Molly’s time, would explain why she can’t remember the new platform number.

Incidentally, the InterCity 125 Arthur Weasley takes an interest in at platform 9 (PA5) seems to have its own magical properties—only platforms 1 to 8 are long enough for 125s.

Even though platform 9 itself has moved, magic may require the entrance to still be near platform 9. I would like to suggest that platform nine and three-quarters is not lined up with the others, but is at right angles to them. See the diagram, which show the present platforms 6 to 10, with the possible position of platform nine and three-quarters across them. The new entrance is near the front of the train, which is indeed what Harry sees when he goes through the magical barrier.

Thus, when you go through the magic barrier between platforms 9 and 10, you encounter the Hogwarts Express broadside on. And if that’s the case, it is pointing in the right direction to curve round, as described in the books, to join the railway coming out of the station next door, St Pancras. (The exterior of St Pancras is seen briefly in CS/f, with the Ford Anglia parked outside) The LNER’s locomotives working out of King’s Cross were green and its coaches were varnished wood, but the trains on the Midland Railway, out of St Pancras were red—so the Hogwarts Express would have been much less conspicuous on that route.

Interestingly, there are subterranean lines under King’s Cross on similar alignments to where I have shown platform nine and three-quarters, built to connect the underground Metropolitan Railway with the main lines.

Let us next look at the question of the journey. It is generally accepted that Hogwarts is somewhere in Scotland, as the train travels north and takes most of the day. We also know that Ron and Harry, following the train in the flying the Ford Anglia (CS5) were spotted over Peebles, which is in southern Scotland, about twenty miles south of Edinburgh. Interestingly, Peebles lost its railway in the 1960s: but we already have reason to believe that the Hogwarts Express may not be constrained by the present-day muggle rail network! It is also possible that Harry and Ron were taking a more direct route than the train.

No mention is made of the Hogwarts Express stopping en route—indeed, I have already remarked on the consternation caused by the unexpected stop in PA5. How far can a steam train travel without stopping? The longest regular non-stop train service operated by steam traction was a London to Edinburgh service introduced in 1928 and operated daily during the summer months, except during the Second World war, until 1962.

Steam locomotives use prodigious amounts of water—40 gallons per mile (112 litres per km), so a 400-mile trip would require 16,000 gallons. This is far more than a locomotive can carry in its tender (the vehicle attached to a steam locomotive which carries its coal and water, sometimes known in the USA as a “coal car,” although most of its volume is in fact the water tank). In the days of regular steam trains, arrangements were made to replenish the water tanks without stopping: water troughs (“track pans” in US terminology) were provided between the rails and a scoop was lowered from the tender to collect water from them. The process could be spectacularly messy! However, the troughs were removed in the 1960s, when steam trains ceased to run regularly. When a special run was made in 1968 to commemorate the fortieth anniversary of the first run of the “non-stop” (using the same locomotive, No. 4472 “Flying Scotsman”) it had to have a second tender to carry the extra water needed.

To boil all this water, the locomotive needs fuel, usually coal. Unlike water, coal can not be supplied on the move so the distance a train can travel without stopping is dictated by the coal capacity; in practice, rather than refuelling, it was usually quicker to uncouple the locomotive and replace it with another one already fuelled up.

It takes a little more than a pound of coal to boil a gallon of water, so special tenders with a coal capacity of over 8 tons were needed for this 400 mile run. They had another special feature too, which is very significant for the Hogwarts Express.

Anyone who has watched an action movie involving a steam train, from Buster Keaton’s The General to Back to the Future Part III will know that there is no easy access to the driver’s cab from the train, except by dangerously scrambling over the tender.  But Professor Lupin (PA5), and the trolley witch (PS6) seem to have no difficulty visiting the driver of the Hogwarts Express whilst it’s in motion, and the trolley witch clearly expects the children to be able to find her there, so she can’t have apparated. Indeed Hermione does visit the driver, on her very first journey to Hogwarts (PS6), before she has (officially!) learnt any magic! The “non-stop” suggests an answer.

The LNER’s non-stop service was a publicity stunt: the need to eke out the fuel and the severe speed limits through Newcastle and a few other stations meant little time was gained compared with stopping there to change engines or crew. It took eight hours—we know from the books that the Hogwarts Express takes about nine hours since it arrives at Hogsmeade after dark. That is far too long for one crew to work: don’t forget that a locomotive’s fireman has to shovel his own weight in coal every three miles or so!—and so arrangements were made for a second crew to travel in the train, and change over on the move. To allow this, special tenders were built which allowed access between the train and the driver’s cab of the locomotive. This design was unique to the LNER: the spaced taken by the corridor reduced the space available for coal and water, so only those locomotives used on the non-stop service were fitted with these corridor tenders. No other railway in the world used them—indeed the designer, Sir Nigel Gresley, patented the design (US Patent 1731856). Clearly one of these corridor tenders must now be used on the Hogwarts Express! The non-stop service lasted until the end of steam in 1962—anyone who has heard a “Deltic” diesel in full cry will realise why it was not considered safe for a crew to walk through its engine room.

Non-magical objects can enter magical space, for example Harry’s clothes (Dudley’s cast-offs), Hermione’s parents (CS4), and muggle money (for changing at Gringotts) can all get into Diagon Alley. Provided it can enter magical space, there are no features about the train itself that cannot be explained in muggle terms. In summary, the Hogwarts Express could be a conventional steam train, fitted with a corridor tender (or more likely two, like the Flying Scotsman) with about eight carriages, that has simply been put into magical space. In magical space it can start from platform nine and three-quarters at King’s Cross, and join the Midland Railway’s route from St Pancras via Sheffield, Leeds, and across the Pennines to Carlisle. From there it can, somehow, follow the route of the closed railway to Edinburgh through Peebles, explaining the sighting of Harryand Ron there, and on to the Scottish Highlands.

There is one problem: in HBP8, when Harry is trapped on the train at Hogsmeade station, the floor “began to vibrate as the engine roared into life” before it started to move out of the station. This is not characteristic behaviour for a train hauled by a steam locomotive. Firstly, the floor of a locomotive-hauled train (whether steam, diesel, or electric) does not experience vibration from the engine, because, unlike modern trains, the engine is not under the floor. Secondly, a steam engine, unlike an internal combustion engine, has no clutch and does not “rev up” before it starts to move. As soon as steam is admitted to the cylinders, the locomotive moves. So, what we seem to have is something that looks like a steam train but is powered by something else—what is known by railway modellers as a “steam outline.” As to what that power source may be, well, it could be an underfloor diesel engine—or of course it could be magic!