Stanley House is such a romantic place, says Nicky Haslam. It stands at the western end of the King’s Road, bowered in trees and extensive gardens. Named for Elizabeth Stanley and built at the end of the 17th century, this is a house with perfect butter-pat proportions, its horizontal red-brick façade filled with long sash windows. The Stanleys and their descendants were here until 1691, followed by the Countess of Strathmore, great-great-great-grandmother of Lady Elizabeth Bowes-Lyon, the late Queen Mother. Finally came William Hamilton, scholar, diplomatic servant and private secretary to the Earl of Elgin, during his embassy in Constantinople, who laboured to bring the Parthenon Marbles back to England. Then, from 1840, Stanley House served as a teacher training college, only reverting to private ownership in 2002. This is where Nicky Haslam enters the story, for the house was by this time a wreck – “all falling apart”, with gaping holes in its floorboards – having stood empty for years. Its historic interiors were protected by listed building status, so that panelling and its original staircase had to be carefully reinstated under the supervision of English Heritage.

The new owners just rang Nicky up one day, he remembers, his high reputation having preceded him. They had already decided that Stanley House should retain its intrinsic style and spirit – but, he was told, “I want it to look like a house of that period but with some pizzazz!”. Nicky was to design and decorate the house from top to bottom, and fill it with a glorious melange of bespoke furniture and appropriately superb carpets, ceramics and paintings – many of which are offered by Bonhams at the Collections sale in Knightsbridge in December. Since the idea of a straight historical restoration was anathema to Haslam too, he knew they would all work well together. Haslam claims that he fell into decorating. “I’d never had a proper job you made money out of except working on Vogue.’ But, while living in New York in the late 1960s, he saw what the very best of the city’s nascent professionals were doing there, particularly admiring the taste of Mark Hampton, George Stacey and Billy Baldwin. “American decorators were more vivant then… not so trapped in the past as a lot of English decorators."

Billy made that slight mixture between modern and old, and he liked my New York flat. But I’d never decorated professionally until I got back here in ’72 or ’73. I suddenly thought, ‘People seemed to like what I did in America… well, Billy liked it!’” Luckily, Nicky started out in decorating with “a very good group of young bachelors” including Mark Shand and Nicholas Soames, “chaps who hadn’t got girlfriends who wanted to do this themselves”. Interestingly, friendship was key to his involvement at Stanley House too: Nicky was close to the new owners. “Certain clients and certain houses give you the entrée into another world of decorating – they just put their trust in you.”

Nicky outside his former home, the Hunting Lodge

The drawing room of Stanley House

An Italian baroque carved giltwood and silvered mirror Estimate: £5,000 - 7,000 ($7,000 - 10,000)

Sir Lawrence Alma-Tadema, OM, RA (British, 1836-1912) Clotilde at the Tomb of her Grandchildren Estimate: £40,000 - 60,000 ($47,000 - 70,000)

A George II painted side table, in the manner of William Kent Estimate: £3,000 - 5,000 ($4,000 - 7,000)

His aide-de-camp at NH Design for this project was Colette van den Thillart, whom he describes as “the best decorator in the world, without any question”. He found her through her thesis on the post-war interior designer John Fowler – it was “pure happenstance”, Nicky says – and he lured her from Canada to help him. “We had the same view on everything, and she was even madder than me. You could say that there was a sort of magic about that house… it just worked.” As a template, Nicky had Great Hundridge Manor. Indeed, Stanley House looks remarkably like the Buckinghamshire country house whose William and Mary style forged his aesthetic sensibility. He grew up there amid such exquisite furniture as the canopied Venetian Renaissance bed that Geoffrey Scott designed for Nicky’s father, the diplomat William Heywood Haslam. (The bed is now a V&A exhibit.) Nicky’s friend David Hicks credits Great Hundridge with some of the most beautiful rooms in England, and Haslam based the wall finishes in the intimate sitting room at Stanley House – with its faux bois, faux green lacquer and faux marble – closely on one of them. Then, over the fireplace, he hung a gilt rondelle framing Catherine the Great’s portrait.

There is one thing that Nicky remembers as really extraordinary, a bit of serendipity that was much more than coincidence. In the great room known as the ballroom, Hamilton had affixed – marching in a frieze around the upper walls – one of the first sets of plaster casts taken in situ at the Parthenon in c.1812. These generated a host of icing-sugar white replicas in the palaces, gentlemen’s clubs and institutions of Europe. Nicky had seen them years earlier at a party here, and now he set about designing around them, rejecting his first foray into chintz for something more sympathetic to the room’s classical rigour.

Then the architectural historian John Harris rang, alerting Nicky to a watercolour of the room painted in 1815. “He located the original, I rang the owner and we bought it. It shows William Hamilton sitting at the most modern desk you’ve ever seen in your life… it’s sort of G Plan. But this really was weird: the colouring, striped upholstery and furniture I’d put in my own design was exactly like the picture – the bookcases and low bookcases, the classical busts and the overdoors. A carpet from S. Franses – the best carpet dealer – I’d found that exactly fitted the room looked so similar too. Then I got a set of long classical frieze designs in the King’s Road and bought a lot of Etruscan vases because they suited the room and looked good – 19th century and modern copies… I like fakes.”

We admire a number of items about which Nicky says, insouciantly, “I just found that somewhere,” but a high proportion of the furnishings and the skilful techniques deployed by his studio and craftsmen were bespoke. Asked to describe the almost serpentine dining room chairs, he says “They’re like those baroque throne chairs… Italian. They’re made for us by the wonderful people we’ve always used: you design the shape and cover them with stuff.” Albeit the “stuff” is, in this case, Velours Neptune from Clarence House. The panelled walls were painted by his specialist painters exactly to resemble watered-down wine; the window frames were gleamingly gilded like those at Chatsworth, but on the inside.

The owners took a bit of convincing when it came to the introduction of floral patterns and chintzes, because they had previously lived in New York and chintz had long since ‘gone’ over there. But the master bedroom presented no problems, for its panelling was all there to be recoloured in blue-grey wood graining, which Nicky combined with a huge Aubusson carpet he had spotted on Santa Monica Boulevard when walking home late after the 2015 Vanity Fair Oscars party. “I bought everything I liked, and the clients liked… well, they loved everything!”, he says. These are settings that enshrine luxe rather than luxury – the curtains, for instance, are sewn with pearls and all the finely woven voile sun curtains are of cashmere.

Nicky’s favourite room in the house is the adjoining bathroom. It showcases his creative imagination and historical references, with a pair of white console tables that Nicky adapted from those in Marie Antoinette’s dairy at Rambouillet, a gay little bathroom cabinet suspended on a curling riband of tin and a plumply upholstered 18th-century orchestra stool set before the dressing table. He designed an immense bath with a lip of brèche violette marble. “When it was installed, it came through the ballroom ceiling – the famous first steel ceiling in England. Well, it got wedged halfway… but the clients just said, ‘Thank God nobody was hurt’.”

The bedroom for the family’s young child was based on that of the Duke of Windsor in Paris, with three flags sewn into beige carriage cloth upholstering the wall above the bed. On the top floor were “quite chintzy” country house bedrooms, where Nicky used the Maury wallpaper that John Fowler had favoured when he lived at the Hunting Lodge in Hampshire, “but I had it recoloured in mauve”.

A collection of seven matched painted plaster busts of classical subjects Estimate: £3,000 - 5,000 ($4,000 - 6,000)

An Italian stone cistern with later Regency gilt lion mask handles Estimate: £3,000 - 4,000 ($4,000 - 5,000)

A large 19th-century composition stone stag Estimate: £2,500 - 3,500 ($3,500 - 5,000)

As a result, Stanley House with all its myriad contents became much more than a lovely private retreat. It once again trails clouds of glory, with its remarkable history revived and respected. But Nicky Haslam can never be boring, so he permitted himself a little dramatic licence in the front hall, posing a heraldic stone stag on a pedestal table covered with old tapestry roughly torn into strips and sewn together with raw edges. Why? Because “I’ve always wanted to do it.” The doorcases here are padded in conker-coloured velvet, the portière rail and its curtain rings are velvet upholstered too, just to make it “different”.

Along with the novel, imaginative and contemporary, Haslam brings his own legacy of historical literacy along with, “a kind of discreet continuity in British interior design.” But, he emphasises, “I just thought it’d be fun to do it.”

Ruth Guilding writes on art and design for The World of Interiors and the TLS, and at bibleofbritishtaste.com.