THE train now standing at Platform 9¾ is the express service to Hogwarts School of Witchcraft and Wizardry. You’ll have seen pupils pushing trolleys laden with all their otherworldly goods through the wall at King’s Cross Station in the Harry Potter film franchise.

But there’s no need to rush – because steam locomotive GWR 4900 Class 5972 Olton Hall isn’t going anywhere anytime soon. Yes, it’s a real train, which carried passengers from 1937 to 1963 but it’s now enjoying a well-earned rest here in Leavesden.

We’re on the Warner Bros Studio Tour London – The Making of Harry Potter tour on the film complex near Watford where the eight smash hit movies were filmed. This is the second half of the tour – if you missed my review of Part 1, head to my earlier post here.

The sprawling station set was added to the tour in March 2015, and rapidly became a firm fan favourite. On a tour full of big moments, the first sight of the iconic Hogwarts Express, in its rich red livery, is a showstopper worth the visit in its own right.

For railway buffs out there, I’m reliably informed that the carriages are British Rail Mark 1s, the first passenger carriage designed to work across all the different rail lines in England after the railways were nationalised in 1957. No, I had no idea either …

You can walk through them, taking in the compartment where a young Harry and Ron were lectured by Hermione as they tried to capture the errant chocolate frog in the first movie, and she used a spell to mend Harry’s broken glasses.

The station set is a hotspot for selfies, and also offers ‘green screen’ photography sessions to put you in the heart of the action, but these are at extra cost with packages starting from £20. Still, it’s cheaper than travelling by train to Scotland for real.

Attention to detail here is remarkable. If you thought Disney had a keen eye, this takes it all to a whole new level. You could, quite easily, be standing on the King’s Cross platform as steam belches from the Hogwarts Express, with sounds just like the real deal.

During the current ‘Magical Mischief ‘ season, you can learn how to make a Howler – the strident speaking letter from Mrs Weasley to red-faced Ron – with a free origami lesson at the end of the platform, while an evocative station shop offers souvenirs to buy.

Once you’ve had your Hogwarts Express fix, there’s chance to peruse some amazing books, newspapers – “Daily Prophet! Read all about it!” – and posters, with a display of some the items dreamed up by the graphic artists who worked on the film props.

Then it’s off to the Backlot – the only part of the tour sited outdoors – where the Hogwarts Bridge, Professor Sprout’s Greenhouse, the Dursleys’ Privet Drive house, the Knight Bus, The Burrow and the Hogwarts Courtyard Fountain are the main attractions.

You can walk through No 4 Privet Drive, a full-sized replica of the Bracknell, Berkshire home that featured in the films, and stroll through the greenhouse, too, where you can pull up a squirming mandrake from the planting bench.

The purple Knight bus, all three floors of it, is an eye-catching centrepiece, although you can only stand on the platform at the back and climb the first few stairs if you want to snatch a selfie. There are free photo opps, too, astride Hagrid’s motorbike and sidecar – and inside that flying Ford Anglia.

There’s another cafe here, and a stall selling among other things, the Butterbeer the students all love when they party in Hogsmeade. Rest assured that the beverage, which tastes vaguely of shortbread and butterscotch, is non-alcoholic but – sorry – sickly sweet.

Passing through an area showing what wonders the make-up and prosthetics wizards can do – the heads arrayed on shelves look a little disconcerting – you reach the next of the tour’s headline acts: Gringotts Bank and the Lestrange Vault which lies beneath.

There’s more free photo fun in the vault, where you can pose between a carefully constructed pile of treasure and the trove behind, brandish the Sword of Gryffindor, and make it look as if you’re right in the heart of the action.

Gringotts Banking Hall has to be seen to be believed. Like the care lavished on Platform 9¾, it’s as if you’ve walked into a real-life Victorian bank with towering marble pillars, rich wooden panelling and huge chandeliers.

Only the goblin tellers give the game away.

Have a good look round and keep what you see in mind because the next stop on the tour reduces the banking hall to fiery ruins as, in a special effects extravaganza, the Ukrainian Ironbelly dragon once chained in the vaults rampages through the place.

For many, this will be the highlight of the tour, the sort of attraction that most attractions would save for last.

But wait, there’s more to come, starting with a recreation of Diagon Alley, the secret London byway where the young Harry Potter buys his first wand.

Ollivanders wand store is here, alongside shopfronts advertising Quidditch equipment, broomsticks – Nimbus 2000, anyone? – gowns, potions and more. Weasley’s Wizard Wheezes is the headliner just now, during the ‘Magical Mischief’ season.

Leaving Diagon Alley, you pass some of the amazing work created by the art team as they dreamed up the concepts that would be recreated in real life – ask to take a look, particularly, at the movie storyboards which are simply wonderful .

Hogwarts does, however, indeed save the best until last. Built for the first film, a huge 1:25 scale model of the castle stands fully three storeys high, viewed from a ramped walkway which takes you all the way round so you can take in the meticulous details.

You can watch day slowly turn to night, and see the lights start to burn in the windows as the sun goes down on the school. This season, too, sees the place regularly lit by the fireworks illicitly smuggled in by the older Weasley twins.

It’s a fitting finale to this celebration of all things Harry Potter, and testament to the ingenuity and talent of the movie crews who made the magic happen so realistically on the big screen, the names of whom are all featured in the faux wand store exit.

Nothing faux about the inevitable gift shop through which you must pass to leave the tour, though

It is vast, with a warren of rooms packed with everything from Bertie Bott’s Every Flavour Beans at £8.95, through replica wands at £30-plus to a £420 Lego model of the Hogwarts Express. And that’s just the regular merchandise.

If you’re looking for exclusive limited edition items, you can find them here, too. You’ll need a lot of golden Galleons for those. Or perhaps mortgage your Privet Drive home.

All in all, it’s been a pricey but memorable day out that has wowed all three generations of our family party. You’re never too old for a bit of magic in your life.

For full details of the Warner Bros Studio Tour – The Making of Harry Potter, attractions, events, availability and pricing from £53.50 a head, enjoy a spell at the official website.