Hogwarts Express Research

Vehicles:
5972 Olton Hall has been used in the films, along with four Mk1 coaches.
The first Hornby version used a Castle class chassis as their Hall class chassis was older.

My LEGO version is a scale model of Olton Hall, featuring 2 drive motors under the tender, 2 technic gearmotors turning the driving wheels and lights in the firebox, some flashing, some steady.  The lights replicate the flickering of the fire to the beat of the cylinders (as the airflow drawn through the fire pulses with the chuffs of steam in the smokebox) when moving at a reasonable speed.

My LEGO coaches are 8mm:1ft scale models of Mk1 coaches.  I've kept the main body 8-wide for convenience.  Mk3 coaches are 2.73m wide - nearly 9-wide - so I've kept the extra 1 stud for the bits that stick out, like door hinges on Coach 1, since clearances are already tighter on a LEGO layout with tighter curves.  Coach 1 features Harry, Ron, Hermione and their pets in the windows (the toad is Neville's).  The coaches pass over point lever frames OK.  The bracing on the underside is a scale representation of that on the real Mk1 coach and it adds strength to the base of the model just like it does to the real coach.  I like models that work real as well as look real!

Colour:
The body colour of 5972 Olton Hall in the films is darker than the bright red of the buffer beam.
However, the colour is consistently described by the author as scarlet:
From Harry Potter and the Philosopher's Stone, p71:
"A scarlet steam engine was waiting next to a platform packed with people."
From "Harry Potter and the Chamber of Secrets, p57:
"The Hogwarts Express was streaking along below them like a scarlet snake."
From "Harry Potter and the Half-Blood Prince", p127:
"..., where the scarlet Hogwarts Express stood belching steam over the crowd."
Assuming that scarlet is the same here as when used to paint Ferraris, the brick red LEGO colour is more appropriate than the dark red colour, which is more like crimson.

Scenery:
Glenfinnian station in Scotland was used for Hogsmeade station, with children from a local school as extras for the platform scenes.
Glenfinnian viaduct is featured in the flying car scene of HP2.

Possible Improvements:
The coaches would benefit from 1x3 curved slopes on the roof, though the ventilation ports on the roof would have to move - they are in a realistic pattern at the moment.

Coach 2 and the Brake coach could have hinges on their doors like Coach 1 when I acquire some more hinges, but the doors are not designed to open regularly - that would require gaps to be left in the body sides as the maximum door width whilst opening is 2.24 studs (sqrt 5) - 2 studs wide and 1 stud thick.

The loco could benefit from rounder 6-wide cylinder pieces if they existed.  If larger BBB wheels are ever made (42-46mm) I'd jump at the chance to replace the 40-Tooth cogs with them.

If the loco struggles a bit now that I've built coaches 2 and 3, I'll add a motor at the back of coach 3 to reduce drag in the curves.  A wire the length of the train (as in my Pendolino) might be inconvenient but it's better than burning out the motors.