As we know from early historical accounts,and from the evidence of early woodcuts and engravings,Hogwarts students used to arrive at school in any manner that caught their fancy.Some rode broomsticks (a difficult feat when carrying trunks and pets); others commandeered enchanted carts and,later,carriages; some attempted to Apparate (often with disastrous effects,as the castle and grounds have always been protected with Anti-Apparition Charms),others rode a variety of magical creatures.

In spite of the accidents attendant on these various modes of magical transport,not to mention the annual Muggle sightings of vast numbers of airborne wizards travelling northwards,it remained the responsibility of parents to convey their children to school,right up until the imposition of the International Statute of Secrecy in 1692.At this point,it became a matter of urgency to find some more discreet method of transporting hundreds of wizarding children from all over Britain to their secret school in the Highlands of Scotland.

Portkeys were therefore arranged at collecting points all over Britain.The logistics caused problems from the start.Up to a third of students would fail to arrive every year,having missed their time slot,or been unable to find the unobtrusive enchanted object that would transport them to their school.There was also the unfortunate fact that many children were (and are) ‘Portkey-sick',and the hospital wing was frequently full to bursting for the first few days of every year,while susceptible students overcame their hysterics and nausea.

While admitting that Portkeys were not an ideal solution to the problem of school transportation,the Ministry of Magic failed to find an acceptable alternative.A return to the unregulated travel of the past was impossible,and yet a more secure route into the school (for instance,permitting a fireplace that might be officially entered by Floo powder) was strongly resisted by successive Headmasters,who did not wish the security of the castle to be breached.

A daring and controversial solution to the thorny problem was finally suggested by Minister for Magic Ottaline Gambol,who was much intrigued by Muggle inventions and saw the potential in trains.Where exactly the Hogwarts Express came from has never been conclusively proven,although it is a fact that there are secret records at the Ministry of Magic detailing a mass operation involving one hundred and sixty-seven Memory Charms and the largest ever mass Concealment Charm performed in Britain.The morning after these alleged crimes,a gleaming scarlet steam engine and carriages astounded the villagers of Hogsmeade (who had also not realised they had a railway station),while several bemused Muggle railway workers down in Crewe spent the rest of the year grappling with the uncomfortable feeling that they had mislaid something important.

The Hogwarts Express underwent several magical modifications before the Ministry approved it for school use.Many pure-blood families were outraged at the idea of their children using Muggle transport,which they claimed was unsafe,insanitary and demeaning; however,as the Ministry decreed that students either rode the train or did not attend school,the objections were swiftly silenced.

When Ottaline Gambol commandeered a Muggle train to serve as the new mode of transport for Hogwarts students,she also had constructed a small station in the wizarding village of Hogsmeade: a necessary adjunct to the train.The Ministry of Magic felt strongly,however,that to construct an additional wizarding station in the middle of London would stretch even the Muggles'notorious determination not to notice magic when it was exploding in front of their faces.

It was Evangeline Orpington,Minister from 1849–1855,who hit upon the solution of adding a concealed platform at the newly (Muggle) built King's Cross station,which would be accessible only to witches and wizards.On the whole,this has worked well,although there have been minor problems over the ensuing years,such as witches and wizards who have dropped suitcases full of biting spellbooks or newt spleens all over the polished station floor,or else disappeared through the solid barrier a little too loudly.There are usually a number of plain-clothed Ministry of Magic employees on hand to deal with any inconvenient Muggle memories that may need altering at the start and end of each Hogwarts term.

King's Cross,which is one of London's main railway stations,has a very personal significance for me,because my parents met on a train to Scotland which departed from King's Cross station.For this reason,and because it has such an evocative and symbolic name,and because it is actually the right station to leave from if you were heading to Caledonia,I never knew the slightest indecision about the location of the portal that would take Harry to Hogwarts,or the means of transport that would take him there.

It is said (though where the story originated I could not tell you; it is suspiciously vague) that King's Cross station was built either on the site of Boudicca's last battle (Boudicca was an ancient British queen who led a rebellion against the Romans) or on the site of her tomb.Legend has it that her grave is situated somewhere in the region of platforms eight to ten.I did not know this when I gave the wizards'platform its number.King's Cross station takes its name from a now-demolished monument to King George IV.

There is a real trolley stuck halfway out of a wall in King's Cross now,and it makes me beam proudly every time I pass...

In choosing the number of the concealed platform that would take young witches and wizards to boarding school,I decided that it would have to be a number between those of the Muggle platforms – therefore,it was clearly a fraction.This raised the interesting question of how many other fractional platforms lay between the whole-numbered platforms at King's Cross,and I concluded that there were probably quite a few.Although these are never mentioned in the book,I like to think that it is possible to take a version of the Orient Express off to wizard-only villages in continental Europe (try platform seven and a half),and that other platforms may be opened on an as-required-basis,for instance for large,one-off events such as Celestina Warbeck concerts (see your ticket for details).

The number nine and three-quarters presented itself without much conscious thought,and I liked it so much that I took it at once.It is the ‘three-quarters'that makes it,of course. R4MlvmDP9mSBiB6fbYuj8eD9QKDDbtoWK82KBSCuHN12CTFekizgFFjpINgkIyxn