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One of the largest and most opulent basement extensions ever seen in central London is being planned by a multimillionaire Conservative donor.

The triple decker subterranean complex beneath a house Victorian villa in Holland Park will include a 25m swimming pool, an entertainment room, wine cellar, cigar room, massage rooms, two-level gymnasium, dance/yoga studio, hot tub, sauna and steam rooms.

It will add more than 16,000 sq ft of living space to the five storey detached house and involve digging 28ft below the property, making it one of the largest basement extensions ever proposed.

The property is owned by Edmund and Carol Lazarus, who are understood to have bought the house in November 2010 for £16.2m. It is worth around £20m.

Mr Lazarus, 45, made his fortune as an investment banker before setting up his own private equity firm Bregal Capital in 2002.

Mr Lazarus studied at Oxford University where he became a close friend of Education Secretary Michael Gove. He and his wife, who have a young family, have donated at least £95,000 to the Conservative Party in the last two years.

Mayor Boris Johnson personally appointed Mr Lazarus, a former Westminster Councillor, chairman of the London Green Fund, a £100 million project to invest in schemes that will cut London’s carbon emissions.

“The upper two basement floors would be reserved principally for leisure facilities for the enjoyment of the applicant and his young family,” explained a report on the project by Mr and Mrs Lazarus’s architects Adam Architecture.

The bottom floor will contain “service facilities” including a laundry room and catering kitchen.

There will also be a “car stacker” system with capacity for six cars to be parked below ground – drivers will operate the system using a remote control which will raise a platform embedded into the house’s drive.

Once the car has been moved onto the platform it can be lowered into one of a series of underground parking bays at the touch of a button.

Federica Ambrosini, Mr and Mrs Lazarus’s planning consultant at Jones Lang LaSalle estimates the project will take 50 weeks to execute.

Since basements cost up to £600 per sq ft to excavate and fit out the project will cost almost £10m to complete.

A planning application for the project has been lodged with Kensington and Chelsea Council which will rule on the proposals later this year.

The number of applications for subterranean extensions has more than doubled in the borough in the last year as homeowners and developers rush to get planning permission approved before rules are tightened to restrict new basements in the area to just one storey amid concerns about subsidence and noise nuisance to neighbours.