THERESA May has said she does not want a Cabinet of "yes men" as she continued to resist pressure to sack Foreign Secretary Boris Johnson over claims of disloyalty on Brexit.

The Prime Minister insisted she was "in charge" of the EU withdrawal process but stressed how she wanted to hear "different voices" contributing to the development of policy around the Cabinet table.

Mr Johnson's keynote speech to the Conservative conference in Manchester this afternoon will be closely scrutinised for signs of a split after he used a newspaper article recently to set out his personal red lines for Brexit negotiations.

But in a round of broadcast interviews, Mrs May stressed that the Foreign Secretary, like all other Cabinet ministers, was fully signed up to the negotiating position which she set out in a speech in Florence last month.

Mr Johnson himself told BBC Two's Newsnight that the Cabinet was "totally united behind every comma, every full stop, every syllable of the Prime Minister's excellent Florence speech".

After seeing her conference message that the UK Government was building "a country that works for everyone" largely drowned out in media reports by speculation over Mr Johnson's leadership ambitions, the PM was asked whether or not there were any red lines which her Foreign Secretary could not cross.

She told BBC One's Breakfast: "I don't set red lines. Everybody uses this phrase 'red lines'; I don't set those sort of red lines.

"All I would say is leadership is about ensuring you have a team of people who aren't yes men but a team of people of different voices around the table, so you can discuss matters, come to an agreement and then put that Government view forward, and that's exactly what we've done."

She said Mr Johnson's speech, supposedly entitled Let The Lion Roar, had been cleared with Downing Street in the usual way and would set out "how he believes we can build a global Britain and the ambition and optimism he has for Britain, which I share".

The PM went on: "If you look at the issues that Boris has been talking about, I addressed those in the Florence speech, which all members of the Cabinet signed up to."

Following reports that Mr Johnson was referring to himself as "the godfather of Brexit", Mrs May insisted she was in charge of the process.

"Of course, the Prime Minister is in charge. But the way we do things - as we did with our view on Brexit, as we do on other things - is to come together with a Government view and that Government view is then the view that people see," she told BBC Radio 4's Today programme.

Asked if the Foreign Secretary was leading the process, the PM replied: "No, what my European colleagues, European leaders, know is that I negotiate with them leader to leader. When it comes to the formal negotiations, David Davis is negotiating with Michel Barnier.

"What everybody knows is that the Government's position is what was set out in the Florence speech. On this issue, the Government is united...behind that future vision of a deep and special partnership with Europe."

When it was put to her on ITV's Good Morning Britain that Mr Johnson appeared to be "unsackable", Mrs May replied: "No, of course a Prime Minister makes decisions about who is in their Cabinet."

She insisted: "Weak leadership is having a Cabinet of yes men, weak leadership is having a team of people who only agree with you.

"Actually, strong leadership is about having a diverse range of voices around the Cabinet table, who then come together, who discuss the issues and then come up with the answer."

Voters wanted ministers "to focus not on our own jobs, but on their jobs and their futures."

Mrs May laughed off suggestions that Mr Davis was planning to quit as Brexit Secretary after the official date of Brexit in March 2019 and leave Mr Johnson to handle the transition to the new relationship, expected to last around two years.

Reports in the Daily Telegraph and the Sun suggested Mr Davies had told friends that Michel Barnier, the EU's chief negotiator, needed a deal "more than I do" because the Frenchman would still be in post at that point, while Mr Davis would retire and leave transition to "someone else...Boris Johnson".

Mrs May gave the report short shrift, telling LBC radio: "David was joking with someone in a bar and it seems to have been turned into a serious report in a national newspaper."

A source close to the Brexit Secretary, who will also address party faithful today, played down the comments as "a lighthearted remark underlining the fact that we will be leaving the EU in March 2019".

Meanwhile, Home Secretary Amber Rudd, who will deliver a speech to activists this afternoon, was reported to be considering hiring pollster Sir Lynton Crosby to help her prepare for the next election, in a move which has prompted speculation that she may be preparing the ground for a tilt at the top job.

Ms Rudd, who has a tiny majority of 346, wants to shore up the Hastings and Rye seat and is looking at bringing in the firm owned by the campaigner - who steered Mr Johnson to mayoral success but was also involved in Mrs May's disastrous election result - to work on strategy, according to the Times.