More than 20,000 homes are sitting empty across London, according to new research.

The London Housing, worth a combined total of £11.7 billion, have all been vacant for six months or longer.

Using data from the Department for Communities and Local Government and the Land Registry, as well as average property prices per area, Composite Door Experts put together this report on which boroughs have the most vacant homes — and how much they’re worth.

Kensington and Chelsea tops the list, with 1,399 homes worth a combined value of £2 billion sitting empty in the borough, followed by Camden (1,114 homes worth £967 million).

At the other end of the scale, the City of London only has 48 empty homes — no surprise given the lack of residential property in the City. No data is available for the value of these homes.

It’s thought that the increase in buy-to-leave properties, which are purchased to be sold on at a profit rather than to be lived in, is largely responsible for these empty properties — particularly in areas such as Kensington and Chelsea where houses tend to be of higher value.