Sergey Frolovichev, 46, is describing his “bat cave”. It is beneath the garden of his mansion in Hampstead, north London, which he has just spent £15 million — and more than five years — dismantling and rebuilding.
The room, the Anglo-Russian software supremo explains, can be accessed via a staircase from a corner of the living room, concealed by retracting floorboards — with the design inspired by his favourite film, The Dark Knight.
Sergey Frolovichev, right, an Anglo-Russian software expert, is selling his north London mansion for £29.95 million via Draper LondonVicki Couchman/SERGEY FROLOVICHEV/DRAPER LONDON
“It [the 2008 Batman film] was amazing, amazing special effects, everything,” says Frolovichev, who made a windfall by developing dating apps with his billionaire business associate, Andrey Andreev.
Michael Caine and Christian Bale starred in Christopher Nolan’s Dark Knight trilogy; Frolovichev, a fan of the films, partly based the design of the “man cave” beneath his garden on Bruce Wayne’s bat caveAlamy
How Frolovichev’s high-tech subterranean room, which he carved under the garden, could look, including tools and 3D printersDRAPER LONDON
“The man cave, I needed it because I wanted an escape. To do something with my hands rather than with my brain because I thought it would help a lot for my health. I have 3D printers. I like woodworking, just for fun as a hobby.”
Frolovichev doesn’t do hobbies by halves. He designed the entrance to the bat cave specifically so it could fit a factory-style cutting machine through the door. “And it does fit — sideways and then a little bit unscrewed — but it does fit,” he says, speaking by video call from his retreat near Lake Como in Italy.
He even explored Batman-style plans to install sensor-controlled overhead lights that would beam on and off automatically as you walked past — creating the kind of silhouetted effect seen in his beloved movie — but this was ultimately abandoned. (“It was value-engineered out,” a representative of the contractors, who showed me around the house, explained soberly.)
Such are the design considerations for a wealthy gadget-obsessed guy — but Frolovichev is far from any old tech bro. He is the longstanding and famously reclusive IT brains working with Andreev, the Anglo-Russian cofounder of MagicLab, and was central to creating the Bumble and Badoo apps that were sold to Blackstone, the American asset manager, in 2019 for $3 billion. The pair have worked together on numerous ventures ever since moving to the UK at the same time, in 2005.
During Covid, shortly after the MagicLab sale, Frolovichev (whose exact windfall from the sale has not been disclosed) spent £13.35 million on this house on Greenaway Gardens, a five-minute walk from Hampstead Village, and embarked on his mega-rebuild. While construction was going on, he left Britain, ending a tenancy on a central London flat, and moved with his wife to Monaco and then Italy, where they had two children and bought homes in Milan and Como.
Frolovichev bought the Hampstead property during the Covid pandemicDRAPER LONDON (concept design)
The rear of the property reveals the scale of the rebuildDRAPER LONDON (concept design)
It’s a rebuild so extensive, and done to such a high specification, that it cost more than the entire 14,500 sq ft house’s original purchase price so far, and has more than doubled its value. For Frolovichev, along with many of the mega-rich owners in this exclusive leafy street of financiers, tech bros and celebrities, money was no object.
“This is supposed to be our beautiful dream house,” he explains, giving what he says is his first interview. But Frolovichev then goes on to explain to me why — in that ultimate manoeuvre of the very rich — he has decided that, after all the effort and money spent, he won’t move in after all.
A house with its own well — and a retractable pool
As I look around the house, which is “shell and core” — fully plumbed, wired, heated and ready for furnishings — it is mighty impressive in scale. However, it bears zero resemblance to the original suburban neo-Georgian home built in 1934 by the English architect Charles Henry Bourne Quennell.
“From a construction perspective, the house is fully operational. It really is ‘plug-and-play’ now. They’ve spent a fortune to get to this stage,” says Craig Draper, founder and managing director at Draper London. He sold Frolovichev the mansion in 2021 when he was a partner at Knight Frank.
In front of me, as I enter, is a triple-height galleried entrance hall with cantilevered staircase leading up to multiple floors, perfect for a grand stately home-style entrance. Upstairs are eight reception rooms and seven vast bedrooms.
Frolovichev spared no expense on the upgrade of the mansion, as these concept interior designs showDRAPER LONDON
One of the seven bedroomsDRAPER LONDON
There is a swimming pool that drains to become a dancefloor, beneath which is an intricate system of pipes and levers any tech geek would love; a hangout room with infrastructure for a cocktail bar, a cinema, a wine storage area and a multi-layered landscape garden designed by Kate Gould Gardens. There are huge triple-glazed sliding garden doors that can retract to merge the indoors and outdoors.
The indoor swimming pool can be drained to become a dancefloorDRAPER LONDON
Money was never a constraint, Frolovichev makes clear to me. “Sometimes they [the architects, SHH, and contractors] said to me, ‘Why do you want this? It’s too expensive. You can get a cheaper one.’ But I said, no, it’s for me, I want to have it.
“I want to have the pool which raises from the floor, because I will have the kids’ parties there — sometimes with the pool, sometimes without.
“And I want a car stacker. Why? Because I want to have two cars. I will have two cars, at least, [which] means I have to store them somewhere. I don’t want to put them outside because… it’s outside.”
Throughout the build, Frolovichev has been obsessed with detail, epitomised by a vast underground plant room bigger than most medium-sized office blocks, with 47 control panels for the heating and hot water systems, including underfloor heating, an energy-efficient ground source heating system for self-sufficiency, and fresh air delivery to all rooms.
The home’s vast high-tech plant roomDRAPER LONDON
There are plenty of eccentric touches too, including a well in the garden, so that the house has its own water supply. “We started doing the underground ground source heat pump. They bored the holes and while they were digging they said, ‘Oh, there’s water. We just hit water.’ And I said, ‘Can you dig another one? And we’ll have a well for the water.’ And they said, ‘Sure.’”
While Frolovichev emphasises that he is motivated by sustainability, I suggest there’s rather an element of prepping about all this — the drinking water, the secret underground lair and so forth. After all, a host of tech gurus have made headlines for constructing their own sprawling homes designed to guarantee their own survival when the world comes to an end — including Mark Zuckerberg, the Meta chief executive, who has a $300 million ultra-private compound in Hawaii complete with a 5,000 sq ft underground shelter with his own food and energy supplies.
Frolovichev admits that being self-sufficient has crossed his mind, and refers to a 12-hour blackout in Spain last spring caused by programming errors by Spain’s national grid operator. “Not much you can do without the electricity in your house, right? You have some diesel generators, which will help you out, but if you’re working, if you’re doing something, that’s a disaster.”
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Why I’m not moving in after all
He, his wife and two children, aged four and two, will now stay put in Italy, where they had initially moved to wait out the exhaustive renovations.
“We have a bigger house in Como and a smaller apartment in Milan. It’s basically the dream set-up, like a flat in London and an estate in Surrey,” he says. “So now we sit down and we look at the beautiful views [of Italy] and we’re thinking about how we’ve already started things here, and we thought, ‘Why are we going back again?’
“We’d need to set up everything, we’d need to finish the house. We’d need to find schools.”
As a result, the Greenaway Gardens mansion is on the market with Draper London for £29.95 million. Draper says the house is the perfect blank canvas for a billionaire. He stresses that a buyer will get to see Frolovichev’s architectural plans and can choose SHH, the existing architectural firm, to complete his project. Or they could simply hire somebody else to finish it off and do things entirely differently.
The sunken rear terraceDRAPER LONDON
The kitchen with breakfast barDRAPER LONDON
The home could be worth £40 million once completed and dressed, suggests Draper, who adds it could appeal to buyers from here or abroad. However, filling it with stuff and furnishings, he adds, will cost up to £7 million more and take 12 to 18 months (at this point, the numbers being bandied about just seem like the stuff of fantasy).
“The road has always been significantly high value. But in more recent years, we’ve had some major hitters who have moved in,” Draper says, standing on Greenaway Gardens. “These are owner-occupier fund managers. They spend astronomical sums on the properties… I can’t even get into it.”
Plus, Frolovichev says it’s way better for any buyer that they purchase the house without any decor in it — after all, if they’re anything like him, they would rip it out anyway. “Buying a white box, it’s the best-case scenario,” he says.