Attorney General Geoffrey Cox is in line for the sack when Boris Johnson conducts his post-Brexit reshuffle, it is understood.

The Prime Minister is expected to fire around a third of the Cabinet after Britain leaves the EU on January 31.

Mr Cox was the Government's chief law officer under Theresa May and stayed in the post when Mr Johnson took over.

Attorney General Geoffrey Cox at the State Opening of Parliament on December 19

But sources have said he is at the top of the list of senior ministers expected to be axed.

One said Mr Cox – who deploys his mellifluous baritone voice to great effect in the Commons – was 'not a team player' and added: 'It's all very well being able to recite Keats but the Government needs to come together if we're going to deliver on this election.'

Northern Ireland Secretary Julian Smith is also facing the chop after falling out with No. 10 before the election.

The reshuffle, which is due to take place in mid-February, is already being dubbed the 'St Valentine's Day massacre' because of the number of likely casualties.

Other ministers whose positions are seen as insecure include Work and Pensions Secretary Therese Coffey and Business Secretary Andrea Leadsom. Despite being a long-standing friend of the Prime Minister, Defence Secretary Ben Wallace is not secure in his post and could be moved.

Mr Cox arrives at Downing Street on December 17 for the first Cabinet meeting after the Conservative Party won the General Election

Cabinet Office minister Michael Gove is expected to take on responsibility for the post-Brexit trade talks with the EU.

Chief Secretary to the Treasury Rishi Sunak is in line for a promotion after performing well during the election campaign and impressing Downing Street during preparations for the Budget.

Tory 'mistrust of PM's One Nation vision' The majority of Tory activists view Boris Johnson's One Nation outlook with suspicion or outright hostility, according to a poll. The Prime Minister has vowed to 'level up' the country, pledging to invest in the North and Midlands to counter the dominance of London. Nearly 60 per cent of Tory supporters said they were 'distrustful of interventionist politics' and 'nervous of the Government straying too far from Tory principles', according to the ConservativeHome survey. But 33 per cent said the state should 'frequently intervene in the economy' and think that if it doesn't the Tories' election gains will vanish. Another 5 per cent said there was little to be said for the One Nation outlook and that they 'disliked' intervention. One Nation Conservatism is the principle of preserving established institutions and traditional principles while pursuing social and economic programmes to benefit ordinary people. Advertisement

Last night it was claimed he was being lined up to run a new 'super-ministry' containing the business and trade portfolios. It will have a remit to attract inward investment and 'level up' Britain's economy by targeting help towards poorer areas which voted Tory at the election for the first time.

Mr Sunak, 39, is widely regarded as a rising star in the Conservative Party, and appeared in two TV election debates.

Also tipped for promotion is Brandon Lewis, the security minister and former Conservative Party chairman who impressed during the campaign.

The reshuffle is also expected to see extensive changes to the machinery of Government.

Officials are currently examining plans to split borders and immigration out of the Home Office and transfer it into a separate department.

And one report suggested prisons and probation could be hived off from the Justice Department and returned to the Home Office.

Mr Johnson conducted a mini-reshuffle immediately after the election, in which he promoted Simon Hart to Welsh Secretary.

Nicky Morgan was given a peerage and kept in place at the Department for Culture after standing down at the election.

Zac Goldsmith was also given a peerage so he could stay on as environment minister – despite losing his Richmond Park seat to Lib Dem Sarah Olney.