Westminster council has dealt a blow to the city's property developers eager for a slice of the expensive central London borough.
It's begun a consultation on planning policies which will require developers who want to covert offices into homes to replace the lost work space.
The move aims to stop a recent trend which has seen property developers snap up offices and turn them into luxury housing for the capital's rich and wealthy.
Councillor Robert David, deputy leader of Westminster Council said in a statement:
Westminster has had a long standing and successful mixed use policy which actively requires residential alongside commercial development in the Central Activities Zone.
However, unprecedented changes have been seen recently. While the office market is still very strong, the residential market - once something which needed policy intervention to grow in central London - is now outbidding office revenues at levels that would have been unthinkable a decade ago.
Over the last year Westminster, which is home to a number of company headquarters and government offices, has slowly being re-characterised by new high-end housing developments.
It's benefited from the £2bn regeneration of neighbouring Victoria as well as a boom in the city's prime property market.
Last year property prices in the borough rose by about five per cent more than the London average according Zoopla's Zed-Index.
However, anxieties over the outcome of the 2015 general election and new stamp duty reforms could curb future demand for London's most expensive areas.