Uncrunched by the credit crisis, the owners of a Kensington mansion are planning to dig a gigantic subterranean five-storey bunker.

The mega basement would house a car collection, art gallery, swimming pool, cinema and gym.

The Victorian mansion at 10 Kensington Palace Gardens already has permission for a 65,000 sq ft three-storey basement to be dug.

This is equivalent to more than 92 two-bedroom flats, each with 65 sq metres of floor space.

But this month the owners, Jon and Lois Hunt, asked for permission for two more stories to be dug underneath these planned floors.

Drawings submitted by the architect show sketches proposing 22 cars in the enormous basement.The cars would access the basement via a ramp from the outside.

'The additional floor space is required for the applicant's need for additional private car museum and gallery space,' states the architect's report, adding that basement will allow the property to be borough back into family use.

Project manager Stuart Adolph said the underground structure would be behind the house and would not affect the existing building.

"With any kind of work you do you make the property more valuable," he said, although would not say how much the work will cost.

He added that basement extensions are becoming increasingly popular due to the restrictions councils have imposed on building above ground.

Kensington and Chelsea Council recently commissioned a report into subterranean basements being dug in the borough after a sharp rise in planning applications.

Kensington Palace Gardens is a private road, neighbouring royal land, with a security booth at its end.

The six or seven bedroom property, last used as the Russian embassy, was designed by classical architect Hardwick and first sold in 1846.

Currently empty, the Grade II listed building's doorbell was hanging off from its wire when our reporter visited last week.

Should the Hunts decide to move in, their next door neighbours will be the Indian High Commissioner and the Ambassador of France.

Kensington and Chelsea council is currently considering the application.

A spokesman said: "Kensington and Chelsea Council have most rigorous requirements of any local authority for scrutinising subterranean development applications."