In a speech to the Conservative party conference in Birmingham, Cameron said the Help to Buy scheme had successfully reached those who needed it most.

“Of course there were those who criticised it, usually speaking from the comfort of the home they’d bought years ago,” he said.

“But let’s see what actually happened. They said Help to Buy would just help people in London, but 94 per cent of buyers live outside the capital. They said it would help people with houses already, but four-fifths are first-time buyers.

“They said it would cause a housing bubble, but as the Bank of England has said, it hasn’t.”

Cameron said the Conservatives were the ‘party of home ownership in our country’ and said his new policy to build 100,000 ‘starter homes’ for young buyers would prove to be a ‘landmark’.

“Here’s our renewed commitment to first-time buyers: if you’re prepared to work and save, we will help you get a place of your own. This conference we have announced a landmark new policy, it’s called starter homes.

“We’re going to build 100,000 new homes – and they’ll be 20 per cent cheaper than normal. But here’s the crucial part. Buy-to-let landlords won’t be able to snap them up. Wealthy foreigners won’t be able to buy them. Just first-time buyers under the age of 40.”

Elsewhere in the speech Cameron said the Conservatives will raise the 40 per cent tax threshold from £41,900 to £50,000 by 2020 if they win the next election. He also promised to raise the tax-free allowance from £10,500 to £12,500 during the same period.