I'M being bowed to by an animatronic hippogriff. And not just any old hippogriff, but Buckbeak - Hagrid's Buckbeak.

He twitches and tilts his head at me, before stretching his neck magisterially towards the floor, the thousands of individually hand-glued feathers covering his mechanised body as malleable and shimmering as iridescent rainbow streaks in an oily puddle.

Aged 28 and standing in the otherworldly twilight of the Warner Bros. Studio Tour's 'Making of Harry Potter' Forbidden Forest, flanked by 12-foot-wide faux-mossy tree trunks, it's impossible not to be mesmerised by the horse-sized robot.

But my 8-year-old self? She would have lost her mind.

From 1997 onwards, I did all of my growing up with Harry, Ron and Hermione, surviving a not-so magical comprehensive while they went to Hogwarts School of Witchcraft And Wizardry, and saved us muggles from the wrath of Voldemort.

On June 26, it will be 20 years since Harry Potter And The Philosopher's Stone originally hit book shelves, so I'm on a Potter pilgrimage to discover the locations that appeared in the subsequent film adaptations. Leavesden studios, just a 15-minute (Knight) bus ride from Watford station, is the Hollywood rendering of Rowling's dazzling imagination, a storehouse of trinkets, wigs, sets and artefacts from all eight films (2001-2011).

Three hulking, malevolent wizard chessmen (competitors in Ron's deadly match in the first movie) stand guard in the car park. Dripping rust; the knight lugging a spiked ball and chain, poised to let it fly as visitors - lightning bolts scrawled on their foreheads to match Harry's Voldemort inflicted scar - pose giddily beneath.

Inside is as crammed and higgledy-piggledy as the Weasley's Burrow, which - in this collapsed and confounding geographical remapping of the wizarding world - is found next to the potions room, where drifts of cloudy bell jars swim with dubious, tangled substances.

However enchanting and impressive it is to see 'behind the scenes', it does somewhat dampen the magic to be constantly reminded of the distinct, graspable line between fiction and reality.

Look up from Professor Snape's robes, which hang upsettingly motionless beside Professor Dumbledore's in the overwhelming expanse of the Great Hall, and an exposed ribcage of a ceiling, spiked through with scaffolding, gapes wide where Rowling's enchanted sky ought to be.

A series of beautiful architectural blueprints and model sets - including an intricate matchstick dummy of the owlery, where itty-bitty illustrated owls sit, ready and waiting to deliver wizarding mail - reveal the films' skeletal frames, while the hundreds of peeling wand boxes that buttress the windows of Ollivanders store, we're told, were each painstakingly hand labelled by set dressers (not wand-makers).

At Alnwick Castle, an hour's drive north of Newcastle - its bulky Norman walls the scuffed gold-black of an old pound coin - the line between living the magic and just looking, is brilliantly disguised.

Instead of obeying 'Keep off the grass' signs, budding Quidditch players (ahem, me included) run amok on the frog-green lawns (broomstick training sessions are free, but it's wise to book in advance), mimicking Harry's fateful first flying lesson with Madam Hooch, which was filmed in the castle's outer bailey. The blocky inner bailey is also where, in The Chamber Of Secrets, Harry and Ron crash Mr Weasley's cerulean flight-enabled Ford Anglia.

There's no stately stuffiness at Alnwick, partly because it's still a home, not a monument. Owner Ralph Percy, 12th Duke of Northumberland, lives here with his family (October to March - for the hunting season), and the evidence is everywhere.

Furry bean bags for the dogs fan out in front of an incongruently huge flat screen TV in the ornate, gilded library, while in the drawing room, cast your eyes up and away from two wildly valuable 17th century Cucci Cabinets that once stood in the Palace of Versailles ("France wants them back," our guide says archly), and there's a set of floodlights for playing ping-pong...

Following a breakfast of eggs and bacon that Hogwarts' house-elves would be proud of at the Hog's Head Inn, Alnwick, the fourth wall slips even further in Durham City.

We turn the corner on cobbled Owengate, calves aching from the climb, and the thickset Norman Cathedral surges into view. It's bulky and deeply rooted, its bricks stacked, crenellated and crinkly, like sandy corrugated card.

When developing how the 'Hollywood' Hogwarts would look, the designers simply copied and pasted Durham Cathedral's main tower, but it's the 15th century cloisters that make you feel as though you're really walking the wizarding school's corridors. What became, on celluloid, a snowy quadrant where Harry releases his owl Hedwig, on a blustery Northumberland morning is a lush square, ablaze with sunlight, enclosed by flagstones and the ghosts of the Benedictine monks that lived here before Henry VIII dissolved the monasteries.

I swoosh up and down, my imaginary robes whirling as I turn each corner of the square - all that's missing is the scratch of a striped Gryffindor scarf around my neck.

On the North Yorkshire Moors Railway, dreams of attending Hogwarts are closer still.

Goathland Station, a 20-minute drive from Whitby, doubled as Hogsmeade - the wizarding village where the Hogwarts Express pulls in - in the early Harry Potter films. And although there is no burly Hagrid to greet us, snagging a turquoise ticket the size and shape of a dominoes tile, requires its own kind of sorcery.

There's a knack to hunching down and peering through a strange, perspective-distorting window that makes the volunteer ticket officer on the other side - one of the many who help run the railway - appear as though he's several miles away. You get the sensation you're in a tunnel, or travelling by floo powder.

It seems apt to end our trip by rail. After all, JK Rowling had the initial idea for Potter in 1990 while on a train to King's Cross.

Aboard the rhubarb-and-custard-coloured LNER B1 No. 61264 locomotive, which began its chug-life in 1947, I manage all of three minutes in my seat before leaping up to hang out of the window like an extra in The Railway Children.

Without Bertie Bott's Every Flavour Beans to distract me, I stay there for the whole 50-minute journey to Pickering, trying to catch a glimpse of the train's front portion as it turns up ahead, steam unspooling like the alabaster milk poured into cups of Yorkshire from the rattling tea trolley.

I screech as sharply as the loco grinding to a halt when I spot a tawny owl.

Flesh and blood, unlike the miniature Studio Tour ones, it's as still as Snape's robes, perched in a pine tree overlooking the railway line, with not a honeyed feather ruffled as we chug slowly past.

My 28, and 8-year-old self, magically agree: it must be on owl post delivery duties.

TRAVEL FACTS

:: Ella Walker was a guest of VisitEngland and stayed at the Hog's Head Inn, Alnwick (www.hogsheadinnalnwick.co.uk; B&B from £114.95) and Raithwaite Hotel, Whitby (www.raithwaiteestate.com; B&B from £227).

:: Tickets for the North Yorkshire Moors Railway (www.nymr.co.uk) from Goathland to Pickering are £23 per adult.

:: Adult entry to attractions: Alnwick Castle (www.alnwickcastle.com; from £13.95), Durham Cathedral (www.durhamcathedral.co.uk; £7.50) and the Warner Bros. Studio Tour (www.wbstudiotour.co.uk; from £37).

:: Do your Harry Potter journey by train. Book through the Trainline App, enabling you to beat station queues and receive live travel updates.

:: For more information, visit www.visitnorthumberland.com, www.yorkshire.com and www.thisisdurham.com