Twenty-three-year-old Fawn James sits at the window of a second-floor private dining room in Soho House and looks out over the restaurants, patisseries and clubs of Soho. To anyone else, this elevated view of Greek Street would be charming yet unremarkable but for James it is different - she owns it all.

 Ever since her grandfather Paul Raymond, the porn and property tycoon, died a year ago at 82 leaving her his entire personal estate of £75 million to split with her teenage sister, she has become Soho's biggest landlord.

 "It's pretty crazy," she says of the "bizarre experience" of being able to point at every second building she passes in Soho and go, "mine", "mine", "mine", including landmarks such as Ronnie Scott's and Soho House. Just over a year ago, she was a student living on a budget in digs at St Andrews University being doted on by the grand-father she spoke to every other day and lovingly called "Papa". Now she's worth £37 million and together with other members of her family, controls an astonishing 60 of Soho's 87 acres.

 Speaking to the Evening Standard in her first ever newspaper interview, James, dubbed "the Queen of Soho", says she is "still learning the ropes" from her stepfather John, who effectively runs her grandfather's business, Soho Estates, but adds that her first mission will be "to make Soho greener". "We're looking at retrofitting our entire stock of buildings to make them more environmentally friendly," she says. "These are very old buildings which my grandfather bought up over the past 40 years and which are currently not energy-efficient. It will be an expensive project but I'm confident we'll achieve cost savings over the years and I know that the company is keen to head in that direction."

 She is also determined, she adds, to "give something back to the community" and is looking to initiate the company's first social responsibility programme. "I think it's important to support charities operating in Soho and in the coming months I'll be assessing which ones we want to assist."

 James's social responsibility manifesto could be a response, she admits, to becoming super-rich without having worked a day in her life. "People ask me whether I've been on a spending spree yet but to go out and spend is hard when you don't feel you've done anything to earn it. So far I've bought myself a Porsche Boxster for £40,000 but I was going to buy a new car anyway. That's my indulgence. I'm not the sort to go shopping on Bond Street, I prefer All Saints to Gucci, and I've never hung out with the children of the super-rich. I've never met the likes of Peaches Geldof, and it was my grandfather's nightmare that I would end up like Paris Hilton. I'm just a normal 23-year-old, or rather a normal-ish 23-year-old," she grins raffishly, "in a Porsche."

 Indeed James's apparent level-headedness is remarkable considering her traumatic childhood. She was just six when her alcoholic mother, Debbie, then 36, died of a heroin overdose, and she never knew her father, Duncan Mackay, the keyboard player in 10CC, who split up from her mother when she was a baby. She was taken in by John James, her mother's second husband and father of her younger sister, India Rose, who, despite having since separated from Debbie himself, adopted Fawn and together with his partner, Jilly, brought her up as his own at his mansion in Woking, Surrey.

She went to a private school, learned to ride horses and show-jump and took up singing and acting. As a soprano, she writes and sings her own songs and was part of an a cappella group called the Accidentals at university.

 For James, the day her mother died was the day stability began to re-enter her life. "I remember being picked up early from school and taken home and being so excited to see John because I thought he had come back to live with me and Mum, but actually it was to tell me the terrible news, and from that moment on," she pauses, "I don't remember anything. Maybe I've blocked it out but I feel lucky that I was young enough to adapt and that I've grown up in a loving, happy family."

 But for Paul Raymond, the death in 1992 of his favourite child, Debbie, was a blow from which he would never recover. The man who opened the UK's first strip club, the Raymond Revuebar, in Soho in the late Fifties and who later moved into publishing porn magazines, including Men Only and Razzle, using the profits to buy up the freeholds of Soho, withdrew from the world and became a virtual recluse. He fell out with his son, Howard, 49, and although they were later said to have reconciled, Howard and his daughters, Cheyenne, 24, and Boston, 22, inherited nothing.

James insists that "everyone in the family was looked after in some way" and that Howard and his children benefited from "other trust arrangements" that Raymond made in his lifetime. She admits, though, that she rarely sees Howard and that when she went out with Cheyenne recently, the will was the one thing that was too tricky to talk about.

 In the last 10 years of his life nobody was closer to Raymond than James, but what was it like to visit him in his penthouse behind The Ritz and be confronted with a lank-haired man who, legend has it, reeked of brandy and never got out of his pyjamas?

 "The picture that's painted of Papa as a recluse is not one that I recognise," she says. "After my mother died, we'd still go on holiday together to Antigua and although when I visited he would sometimes be in his pyjamas, it never bothered me. He was completely with it upstairs and always had a sense of humour, especially when it came to practical jokes. On holiday, we'd be walking past some villas and he'd ring a stranger's doorbell and run away and hide behind a tree. I always thought that was quite spirited for a man in his seventies.

 "When I visited him, which was every other week, he'd have my favourite cakes laid out and he'd often take me for lunch at his best Italian restaurant on Windmill Street. He was a great raconteur with a lifelong stutter, which he'd often turn to his advantage, using it to deliver the punchlines of jokes. Towards the end he became slightly deaf and seemed happier staying in, but he was good at hiding his feelings if he was unwell because the Papa I knew was perky. Papa was an amazing man. He had such a heart. Most people knew him from a business point of view but what I saw was a gentle, loving, lovely human being."

 Is she bothered that her inheritance comes from an industry that is notorious for exploiting women? "The majority of my grandfather's money is from property but it's true that he did very well out of the porn magazines, too," she says. "I admired him hugely as a brilliant businessman, but I must admit that I'm pleased the porn magazine side of the business is in the process of being sold off (those discussions were in place before I came on board) as it's not a business I would want to be involved with. I've never been to Raymond's Revuebar, and I would never pose for a top-shelf magazine."

 And unlike her grandfather - who apparently told his second wife that he'd become a recluse because people liked him only because of his money - she intends to handle the challenges that come with wealth in a more straightforward way.

 "The biggest challenge will be to know who I can trust," she says. "After my grandfather died and my position as an heiress became public, I would walk into a bar at uni and I could see people having a little whisper. It made me feel uneasy but luckily I have a close group of people around me, like my parents, and my boyfriend, Nick Lawson, who is at Nottingham University and who has been going out with me for 18 months and knew me long before I became worth £37 million."

 How would she feel, though, if her biological father, who lives in South Africa, suddenly attempted to re-enter her life? "I wouldn't rule it out," she says. "I'm not saying I definitely want to meet him but I've known for some time, through a friend of the family, that he's open to meeting me and that if I want it, he's willing. But I don't have strong feelings because as far as I'm concerned, my father is John James."

 Is she similarly reconciled to the memory of her mother? She sports a handsome diamond ring that was her mum's. But here the legacy is more complicated. "The memories I have of my mother are mostly good ones, but I do feel angry that my mother neglected her responsibility as a mother. I cannot understand the mentality of what she did. It's made me very anti-drugs. I won't do them. And although I drink alcohol like any young person, I won't do it in an excessive way."

 The loss of her grandfather brought up feelings of abandonment, she says. "Papa's death has been a huge blow. I knew he was old, but his death came as a shock. I went to visit him in hospital but he couldn't talk coherently. It was very hard seeing him in that way. My last words to him were, "I love you", and despite being in a bad way, he managed to say, "I love you, too".

 "His dying wish was that India and I would move into his magnificent penthouse - with three bedrooms, a living room and a big patio area overlooking Green Park - which he left to us. In a few months, when India has finished her A-levels, we'll be moving in. The legacy he's left is an extraordinary one and every day I walk to work to my new office in Soho, I pinch myself at the opportunity he's afforded me. I know that if Papa was alive, he would've wanted me to make my mark. I intend," she gulps, her voice barely audible, "to make him proud."

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