All the London Mayoral candidates have pledged to make the capital more affordable for buyers, but data shows the track record of their predecessors suggests otherwise.

Figures from buy-to-let crowdfunding website Property Partner show that when Ken Livingstone was elected London Mayor in 2000, average property prices in London were 5.6 times earnings – now under Boris Johnson they have more than doubled to 11 times.

The data shows the challenge the front runners, the Tory’s Zac Goldsmith and Labour’s Sadiq Khan, have in store.

Labour’s Livingstone was elected as the first London Mayor in 2000 when the ratio of house prices to earnings was 5.6, based on data from the Department for Communities and Local Government.

By the time he left office in 2008, this figure had risen to 8.3.

House prices have continued upwards under Conservative Mayor Johnson to 11 times with five out of 33 London boroughs in double digits, according to Property Partner.

The figure is highest in Kensington and Chelsea where the average prices were 14.43 times earnings in 2000, 24.83 in 2008 but at the end of 2015 it was 38.08.

Hackney has seen the biggest growth, rising from 5.59 times in 2000, 8.58 times in 2008 and now is at 14.68.

Dan Gandesha, chief executive of Property Partner, said: “This research shines a harsh spotlight on the desperate issue of affordability in the capital, proving London’s current and former mayors – Ken and Boris – both failed on housing.

“Whoever wins tomorrow needs an innovative approach to help resolve the supply crisis. Neither of the two front runners has even been able to define ‘affordable’. What is crystal clear is that most Londoners are being priced out of the housing market as properties now stand at 11 times average earnings.

“The solution to the housing crisis in the capital must be radical. There’s no time to waste. Potentially unpopular solutions, like building on the green belt, should be seriously considered. House building needs to double to meet demand.”