The Prime Minister is already under fire for staying at an £18million penthouse in Covent Garden owned by Lord Alli earlier this year, using it to film party political material.

But it was now been revealed Sir Keir and other senior Labour figures including chief of staff Sue Gray used the former banker’s £4million townhouse in Soho for strategy meetings before the election.

It is the latest sign of a close link between Lord Alli, the PM’s largest personal donor, and the heart of the administration.

Mr McFadden said today that the rules on ministers accepting hospitality will be overhauled to ensure they are more transparent about what is being provided.

He said the rules will be changed to bring them in line with what shadow ministers and backbench MPs must declare, as he described the current requirements as a ‘Tory loophole’.

Under the current arrangements, introduced by David Cameron in 2015, details of hospitality received by ministers in their ministerial capacity are published by departments.

But the information is released quarterly and does not include the value of the hospitality. MPs’ and shadow ministers’ interests must be declared within 28 days, are published fortnightly and include the cost of the hospitality.

Mr McFadden told the BBC: ‘This was a Tory loophole, brought in so that you would have an event where the Tory minister, as it was under the last government, there, the Labour shadow opposite number would also be there, and the Tory minister would not have to declare.

‘That was the Tory rules, we don’t think that’s fair, so we will close that loophole so ministers and shadow ministers are treated the same going forward.’

It came as Rosie Duffield quit as a Labopur MP with a broadside at both ‘cruel and unnecessary’ policies such as the two-child benefit cap and the ongoing row about gifts and hospitality received by Sir Keir Starmer and other senior party figures.

The Canterbury MP resigned the Labour whip on Saturday.

Pat McFadden, the Chancellor of the Duchy of Lancaster, told the BBC’s Sunday With Laura Kuenssberg he was ‘disappointed’ but ‘not surprised’ by her decision.

He said: ‘When I read Rosie’s letter last night and listened to the interview there, I think you can see she has been disillusioned with the party leader, maybe the party more generally, for quite a long time.

‘I don’t think this is something that just developed in the last few months.’

Other Labour MPs have gone further, with one backbencher describing her as ‘poisonous’ and saying the leadership were ‘at least doing something right if they never talk to her’.

Relations between Ms Duffield and the Labour leadership have long been strained, particularly on the issue of transgender rights, and in her letter she criticised a lack of engagement with the Parliamentary Labour Party.

Located in Convent Garden the luxury pad (Pictured: The exterior) has been a longtime hangout for Labour grandes

Rosie Duffield’s full resignation letter to Sir Keir Starmer

She wrote: ‘As Prime Minister, your managerial and technocratic approach, and lack of basic politics and political instincts, have come crashing down on us as a party after we worked so hard, promised so much, and waited a long fourteen years to be mandated by the British public to be returned to power.

‘How dare you take our longed-for victory, the electorate’s sacred and precious trust, and throw it back in their individual faces and the faces of dedicated and hardworking Labour MPs?!

‘The sleaze, nepotism and apparent avarice are off the scale. I am so ashamed of what you and your inner circle have done to tarnish and humiliate our once proud party.’

Her letter continues: ‘I now have no confidence in your commitment to deliver on the ‘so-called’ change you promised during the General Election campaign and the changes we have been striving for as a political party over a decade.’

Ms Duffield also attacked Sir Keir’s record on antisemitism, claiming he left speaking up against former leader Jeremy Corbyn to ‘backbenchers like me’, while taking aim at the Prime Minister’s ‘heavy-handed management tactics’.

And in an attack on the wider party, she accused Labour of showing no interest ‘in my wonderful constituency’ during her seven years in the Commons.

She finished by saying that she hoped to return to Labour when it ‘resembles the party that I love’.

‘As someone who joined a trade union in my first job, at seventeen, Labour has always been my natural home.

‘Right now, I cannot look my constituents in the eye and tell them anything has changed. I hope to be able to return to the party in the future, when it again resembles the party I love, putting the needs of the many over the greed of the few.’