Ken's £117,000 aide lives in £90pw council house

Mr Jasper, the Mayor's director of equalities and policing, pays around £90 a week - a sixth of the market rent - for his three-storey, four-bedroom Victorian terraced house on a quiet side street in Clapham. It is a housing association property, the modern-day equivalent of the council house, although not a typical one.

It is period, rather than post-War, it is not on an estate, and it has a 60ft back garden.

The house is in council tax band F, putting it in the top 12 per cent of all properties in its borough, Lambeth.

A similar private house in the area, moments from the fashionable bars and shops of Clapham Road and about 10 minutes' walk from the Common, would cost at least £750,000 and rent for around £550 a week. A one-bedroom flat in the same street is currently on sale for £320,000.

London Assembly members reacted with amazement last night to the news that Mr Jasper, on a salary of £2,250 a week, is occupying a property intended for a low-income family. "The Mayor is always talking about providing affordable housing, but I didn't realise he meant for his own advisers," said the Tory assembly member, Richard Barnes. "Mr Jasper speaks a lot about helping the needy, but by his presence in this house he is depriving a needy family of a home."

There are currently around 13,600 households on the housing waiting list in Lambeth, the seventh-highest total of any London borough.

Brendan Sarsfield, the chief executive of Family Mosaic, the association which owns Mr Jasper's home, said last year that more affordable housing was "desperately needed" in the area.

"High prices mean buying a house in the private sector is an impossibility for many ordinary Londoners," said Mr Sarsfield. "At Family Mosaic we are building what we can, but many more people need housing than we can help."

There is a particular need for large properties of the type occupied by Mr Jasper, since most new-build affordable homes are one- and two-bedroom flats.

Mr Jasper has a large family, but several of his children are believed to have grown up and moved away.

A spokeswoman for Family Mosaic confirmed that Mr Jasper is one of their tenants, with a secured tenancy that gives him the right to live in his house for the rest of his life, to buy it at a discount or to pass on the tenancy to another member of his family when he dies.

The spokeswoman did not disclose Mr Jasper's exact rent, but said Family Mosaic's typical charge for a "larger property" like his in the area is £90 a week. "In line with nationwide policy, we don't currently means-test our tenants to find out their income," she said. "We have had no discussions with Mr Jasper about him leaving his property."

Family Mosaic received a public subsidy of £80 million last year, an average of just over £3,800 for each of its 21,000 properties.

The investigation into Mr Jasper is probing his role in funnelling hundreds of thousand of pounds of GLA money to an organisation, Brixton Base, which appears to do little, if any, work in return and is run by a friend of his.

Mr Jasper declined to answer our questions on how he had managed to obtain social housing. "I'm not prepared to comment about my personal circumstances," he said.

The Mayor's office refused to comment.