Policymakers have been urged to implement clear rules for developers regarding affordable house building.
According to Shelter, a 50 per cent affordable housing target for new developments in London had been in place until 2008.
Campbell Robb, chief executive of the charity, told the Guardian this led to many more "genuinely affordable" homes being built as a result.
As a result, he believes a similar system should be reintroduced, as only clear rules on how many affordable homes must be built will improve the current supply situation.
Mr Robb insisted that both central government and the Mayor of London should return to this approach in order to "curb London's drastic shortage".
He warned that if they fail to do so, "ordinary Londoners face being priced out of the city altogether".
Mr Robb was speaking after figures from market intelligence group Estates Gazette indicated that 40 social homes were created for every 100 private new builds in London in 2014. This was down from 74 between 2004 and 2011.
Estates Gazette believes this is a consequence of the government's Spending Review in 2010, when the Conservative-led coalition reduced the housing subsidy by nearly two-thirds.
Nadia Elghamry, data editor at the firm, said the proportion of expected affordable housing has nearly halved at a time when starts on private homes in the capital have reached their highest level in 20 years.
She stated that while cash contributions paid by developers was expected to have "plugged this gap", this has not proved to be the case.
Had the ratio of social to private new builds remained unchanged in the last few years, developers would have had to have paid out an estimated £1.3 billion to cover the cost of the missing properties. As it turned out, they paid almost £467 million for social housing provision.