The pair have been in the firing line after Mrs May's gamble of calling a snap election backfired, with disgruntled Conservatives highly critical of the role of Mr Timothy and Ms Hill played in the campaign.

Mrs May was forced into a u-turn within days of unveiling the policy in the Tory manifesto, announcing that there would be a cap on care costs, something which had not been in the original policy document.

The Prime Minister made it clear that she wants support from her "friends and allies" in Northern Ireland's Democratic Unionist Party (DUP) to secure her administration ahead of the Queen's Speech on the 19th of June.

Yesterday, she defended her proposals to govern with the DUP after the recent losses sustained by the Conservative Party. 

Policy programme

In a resignation message on the ConservativeHome website, Nick Timothy said: "I take responsibility for my part in this election campaign, which was the oversight of our policy programme.

"In particular, I regret the decision not to include in the manifesto a ceiling as well as a floor in our proposal to help meet the increasing cost of social care.

"I would like to make clear that the bizarre media reports about my own role in the policy's inclusion are wrong: it had been the subject of many months of work within Whitehall, and it was not my personal pet project."

He also said: "I take responsibility for the content of the whole manifesto, which I continue to believe is an honest and strong programme for government."

Meanwhile, Fiona Hill said in a statement: "It's been a pleasure to serve in government, and a pleasure to work with such an excellent Prime Minister.

"I have no doubt at all that Theresa May will continue to serve and work hard as Prime Minister - and do it brilliantly."