An old passion burns brightly at a restored, treasure-packed Strawberry Hill House

In 2003, the BBC used its then-novel “let the audience vote” concept to produce a show that seemed created just for me. Restoration sent an architect and a historic buildings expert around the country profiling at-risk, listed buildings. Viewers then voted on who got a lump of cash from the Heritage Lottery Fund. In its second season, London’s nominee was Strawberry Hill House. I fell head-over-heels in love. 

At the time it was being used as part of a Catholic university, open only sporadically to the general public. I went. Though it was in bad shape, stripped of almost all of its furnishings and decor, many rooms being used to store excess chairs, tables and academic equipment, it was still magical. This fanciful play castle, built by MP, writer and high-society arbiter Horace Walpole, is considered the first Gothic revival building in England.

He invented the style in an attempt to bring to life the setting he imagined for the novel he was writing: The Castle of Otranto. It was the first Gothic novel. He invented the literary genre, too. While the Victorians became obsessed with Gothic revival (demonstrated most obviously in the Palace of Westminster), Walpole's starting point was different. It’s lighter and more fanciful, still imbued with the elegance and balance of the Georgians. It’s so distinct, in fact, it’s spelled differently. The original catalyst is called is Strawberry Hill Gothick.

I became obsessed. I bought and poured over Otranto. (It’s a ripping yarn, despite its age. And, sure enough, Northanger Abbey, Frankenstein and Dracula wouldn’t exist without it.) I had just purchased a Regency cottage in Datchet and decided I was going to decorate it in the Gothick style. Given that I’d just acquired my first UK mortgage, too, I had no money. So my efforts were modest. I spent the winter hand-stencilling and painting a frieze of Gothick arches around the top of my bedroom walls, decorating the space between each with the quatrefoil inside a circle that’s found throughout Strawberry Hill. I got a deal on some slightly water-damaged prints of Medieval church architecture to hang above my bed. My efforts extended to my staircase hall, where more prints and watercolours, reproductions of roof bosses and gargoyles, and some gothic-arched mirrors carried the theme along. 

I fantasised about replacing my sash windows with arched ones ... with stained glass insets, of course ... and putting lead-roofed porches on the front and back with suitable decorative details. Maybe even encasing my boring old chimney stack with something suitably frivolous. Fortunately for my financial health (Datchet was a charming house but a terrible investment), by the time my mother died and I inherited the money that might have fuelled my Gothick dreams, I’d met my husband and we were shopping for our marital home. 

Strawberry Hill, meanwhile, was experiencing its own fairy tale. The attention from Restoration had fuelled more passions than mine. By 2007 a Strawberry Hill Trust had been set up to take over the lease from the University, and the next year they shut the place down for a 2-year, £9-million renovation. Comparing today's house to my memory of the pre-renovation shell is like encountering Sleeping Beauty sprung to technicolour life after a long, black-and-white snooze. All of the magnificence, romance and slightly creepy atmosphere I remember is there, but now in a glorious state of repair. Some key pieces of art and furniture have been returned to the house, or reproduced, and many more rooms are open. 

More significantly, the Trust is just wrapping up a five-month exhibition in which they filled Strawberry Hill with hundreds of objects that were here in Walpole's day. Single and childless but with a passion for collecting and entertaining, he expanded his "little castle" in stages as his collections grew. Their presence truly brings the place back to life. 

Obtaining these objects from around the world must have required a staggering effort. Some are from local sources ... the V&A, the National Portrait Gallery, various aristocratic collections ... and others from museums much further afield. Yale University's Lewis Walpole Library is a major lender. The number of "private collection" labels makes it easy to envision a giant scavenger hunt, as curators started with Walpole's own catalogue of his treasures and then traced them past the great sale of 1842 when cash-strapped descendants needed a 24-day event to clear the place. 

There are some magnificent things to see here. Sir Joshua Reynolds' triple portrait of Walpole's nieces. A jewel-toned, pocket-sized illuminated manuscript that once belonged to the Doge of Venice.  A monumental stone eagle from the height of the Roman Empire. A lazily sensual portrait of a shepherd boy by Sir Peter Lely that always hung near Walpole's bed, and may explain why he never married. Several portraits of the man himself, including a dashing pastel by Rosalba Carriera (right) that will make you want to see more of this little-known female artist.

I found what the collections say about Walpole even more interesting than their status as individual works of art. He was clearly a man who loved a good story, in some cases splashing out on objects later proved "fake" in either artist attribution or provenance. I rather suspect Walpole wouldn't have cared, as long as he could take people through his wildly atmospheric house spinning tales of the past. 

Here's a lock of Mary Queen of Scots' hair. Wolsey's Cardinal's hat. James' I's gloves. An ivory comb used by Queen Bertha, a legendary queen and saint from England's dark ages. There are enough portraits of Catherine de Medici and her troubled brood to anticipate centuries of historical fiction. And that's before we get to the Tudors. The double portrait of a young Henry VIII and the Emperor Maximilian, his nephew-in-law who would eventually lead Catholic Europe's refusal to grant him a divorce, is deliciously ironic. 

Walpole was also a man who loved his friends, surrounding himself with their portraits or things special to them. I was delighted to see a depiction of our local country estate, The Vyne, hanging over one of the fireplaces. Owner John Chute was one of Walpole's best friends and helped him design much of Strawberry Hill. There's even a copy of one of The Vyne's ceilings in one of the bedrooms. You get the feeling that Walpole's ward Anne Seymour Damer's heart-touching sculpture of two sleeping dogs would have meant as much to him as that priceless eagle.

The borrowed collections start their journeys home on 25 February. Even without them, the architecture and the items the Trust has managed to acquire as permanent collections will make this a monumental place to visit. The three-story staircase hall, with its hand-painted Gothic wallpapers and
fragments of medieval glass casting ghostly colours around, is indeed worthy of a supernatural tale. The library is one of my favourites in England, with wooden frames screening each shelf as if the books lived behind a skyline of cathedrals. Walpole's bedroom shows off a miracle of modern technology: the portrait of Walpole's parents and the ornate frame around it, which he believed to have been carved by Grinling Gibbons, is actually at Yale and far too delicate to travel. This is a digitally printed clone. The bed here is more obviously a reproduction, created from Indian chinz on the advice of the V&A.

The long gallery with its rich, red damask wallpaper, fan vaulting and alcoves copied from Westminster Abbey is wildly flamboyant, yet strangely modest in size. The Holbein Room shows how Walpole cut and pasted architectural features he liked into new forms: the ceiling is copied from Windsor Castle, a room-dividing screen from Rouen Cathedral and the fireplace from an archbishop of Canterbury's tomb.

There's a magnificent octagonal room called The Tribune with seafoam green walls and gold gilt tracery (copied from York Cathedral) rising in a dome to a stained glass centrepiece. Walpole built this to hold his most precious treasures, and at the moment it's packed with portrait miniatures, snuff boxes, pietra dura chests, ebony and ivory cabinets and bronze figurines. Exquisite as the architecture is, this is the one room it's hard to imagine after the treasures all get sent home. 

Fortunately, the most precious item in the last room on the tour isn't going anywhere. Though Walpole mostly designed Strawberry Hill himself, with the help of friends, then handed over to local builders to complete, he called in the greatest architect of the age for one thing. The fireplace in the Round Room is by Robert Adam ... and is the most atypical Robert Adam imaginable. It was supposed to be Gothick, of course, but Adam clearly couldn't move completely from his NeoClassical brand. So it's a whimsical pastiche, with a blaze of inlaid marble that almost looks as if it's been pinched from St. Mark's Basilica in Venice. The colours are extraordinary, thanks to renovation work that cost more than £100,000 and was funded specifically by the American friends of Strawberry Hill.

"I don't know what it is about this place and Americans," a friendly guide said to me with a wink. "Maybe it's that Walpole invented Walt Disney 200 years before your man was born."

Lost Treasures of Strawberry Hill closes on 24 February and it's strongly advised to procure tickets in advance before going to the house during this last week; much of the last weekend is already sold out. Check the web site. The house will close briefly as the treasures are packed up and sent home, then will re-open to the public. With the increased visitor numbers the exhibition has brought in, curators are considering future topical exhibitions in the same way Leighton House builds them into its fabric.