Photos: Now that's what you call a conversion! Former church transformed into £50m home with gym and pool is a temple to modern design

A church round the corner from Harrods has been converted into one of London's most expensive homes and is on the market for £50million.

The 11,500sq ft house in Knightsbridge was sold 15 years ago by the Diocese of London, which needed money for urgent repairs, for just £1million after congregation numbers fell.

It was then turned into a four-storey home complete with basement swimming pool and was owned by Alain Boublil - writer of Les Miserables and Miss Saigon.

The nave of the church has been left open with its 42ft high ceiling and beams still on show

Holy water? In the basement of the newly-refurbished home there is a 30ft swimming pool

The focal point of the house is the magnificent drawing room that boasts 42ft vaulted ceilings, original stone pillars and oak beams that flank the specially commissioned stone staircase which ascends around the bronze and glass lift

Inside the house there is a cinema room with a 120-inch TV screen that can show eight programmes simultaneously

The Grade-II listed building still looks the same from the outside and part of it is still used by the church

However in 2009 he sold the home for £13.5million to a Thai businessman, according to the Evening Standard.

Part of the church was retained by the diocese and continues to be used to this day for worship and community activities.

The rest of the building, though, was then upgraded again with a three-year project costing £10million to bring it to its current state.

The house is not formally for sale, but it has been 'placed' with only a handful of super-rich people who can afford it.

Neighbours told today how speculation over the next tenant has become 'the talk of the street'.

Alice Zetalofsky who lives yards from the former church, said: 'Yes we have all talked about it.

'It's become the talk of the street. Who it might be? Nobody seems to know. Guessing it will be someone incredibly rich. If it cost £50m then suppose only handful of people could afford it, couldn't they?

'It is a beautiful building, though I'm not sure if it would be a suitable home. I'm not sure I would want to live in an old church. Bit spooky wouldn't you say?'

Neighbours have been speculating over who the next person to live in the house might be

One of the seven bedrooms within the house. There are four main bedrooms and another three in total

With a well-equipped gym the new owners of the house won't have to mingle with the riff-raff while going for a work out

Any stresses can be overcome with a mini-spa that includes sauna and steam room, treatment room and juice bar

Another neighbour, who didn't give their name, said: 'We have talked about who might move in. It would be exciting if it was a Hollywood movie star.

'I am glad that part of it will remain a church. The church is not very busy but It is important part remains for the community.'

A brochure for the home reveals the grand opulence in which the owner would live, with gold leaf ceilings, a 30ft swimming pool and a hot tub room.

Getting around the house is made easy with a bronze and glass lift shaft hidden inside a spiral staircase while any stresses can be overcome with a mini-spa that includes sauna and steam room, treatment room, juice bar and gym.

After all that relaxation and working out, there is also the opportunity to relax in front of a 120-in TV screen which (for some reason) can screen eight programmes simultaneously.

A second lounge appears a little more cosy than the vast open space in the church's former nave

Well why not? Among the features on offer to the new owners is this treatment room

Developers Rigby & Rigby describe the property as 'undeniably one of the finest private homes in Knightsbridge.' 

When they were contacted today for comment today a spokeswoman said: 'We can't talk about the property. The owners have asked us not to.'

There are seven bedrooms in total - four main rooms and three guest rooms - while the main drawing room is actually the former nave, complete with a ceiling 42ft high. 

While not all the neighbours are happy with the conversion, conservationists will be happy to learn that the exposed beams, nave columns and mullioned windows have been preserved.

One worshipper at St Saviours told the Evening Standard: 'I just pray the next person doesn't want to gut it again, it all seems madness to us.'

The paper added that there could be a problem with selling the house to Muslim or Jewish buyers because of its former use as a Christian place of worship.

It also points out that the plot of land on which it was built was worth £300 in 1837 - a 167,000-fold increase in value.