The dramatic exit of Boris Johnson’s senior adviser Dominic Cummings will have no impact on crucial Brexit negotiations, Environment Secretary George Eustice said.

After days of turmoil in Number 10, which saw the exit of the Prime Minister’s right-hand man Mr Cummings and Mr Johnson’s director of communications Lee Cain, Mr Eustice insisted talks with the EU on a future trade deal would not be affected.

Speaking to Sky News’s Sophy Ridge On Sunday, Mr Eustice said: “The negotiations have been led by David Frost from the beginning. He’s got a very talented, experienced team of technical experts around him.

“He’s led these negotiations from the start and obviously remains in place and continues to do so.

“So I don’t actually think the departure of Dominic Cummings makes any impact on the negotiations, since Lord Frost has been leading those.”

Mr Eustice said next week is “a week when things need to move” for the UK and EU to agree to a trade deal.

He said: “Both sides recognise that time is very, very short. It’s not long ago we were saying we needed to get some kind of conclusion by the middle of October.

“People have persevered with these talks. There does come a point frankly where businesses need to know what they are preparing for.”

The comments came after it appeared Mr Johnson will attempt to reassert control over his Government by meeting with concerned Conservatives following a power struggle which saw two of his closest aides leave Downing Street.

Chief adviser Mr Cummings exited Number 10 amid claims he had briefed against Mr Johnson and the Prime Minister’s fiancee Carrie Symonds.

The Sunday Times reported the PM will “attempt to get his premiership back on track” by establishing a policy board that will appeal to northern working class voters who helped Mr Johnson win last year’s general election.

The paper said the group will be chaired by MP Neil O’Brien, who helped former chancellor George Osborne devise the Northern Powerhouse, and added Mr Johnson will meet the Northern Research Group of MPs on Monday to listen to their concerns.

It comes after leading Tory MPs urged the PM to use the change of personnel to “reset the Government” following complaints the party and Parliament were not being heard during the time Mr Cummings held sway.

Tory former attorney general Dominic Grieve was scathing about Mr Cummings’s time at the centre of power.

He told Times Radio: “I consider that he’s created mayhem in government.

“The whole of his period in government has been marked by a slide in standards so that the Number 10 press office has been used as a vehicle for distributing smears, untruths and lies which was very obvious in the autumn of last year and the period around prorogation and the run up to the general election.

“This year it’s difficult not to say that he’s created nothing except chaos with the Prime Minister.

“Whether it’s the handling of Covid and his own behaviour, whether it’s the Internal Market Bill because quite apart from being utterly wrong in violating international law, that has blown up in the face of the Government and led to a massive rebellion in the Commons and the House of Lords and something of a crisis associated with that.”

According to reports, tensions were heightened in Downing Street when the Prime Minister was shown “hostile texts” briefing against Ms Symonds, which had been forwarded to her.

Theresa May’s ex-chief of staff, Lord Gavin Barwell, also said the departure could lead to more harmonious relations between the Prime Minister and Tory MPs.

Referring to the Prime Minister, Lord Barwell said: “It feels to me that there’s an opportunity here for him to get his Downing Street operation more harmonious and more effective.

“To rebuild relations with Conservative MPs, the parliamentary party.

“And, perhaps, to set a less confrontational and more unifying tone, that is maybe more in tune with his natural instincts.”

Sir Edward Lister was announced as the interim chief of staff pending a permanent appointment, with the Times reporting chief Brexit negotiator Lord Frost, Lord True and Lord Bridges of Headley are each being considered for the role.

The dramatic events have come as Brexit heads to a crucial phase next week, as London seeks a trade deal with Brussels before the end of the transition period on December 31.

The Prime Minister’s official spokesman, James Slack, insisted Mr Johnson was not being distracted by the row.