Senior Conservative Damian Green has effectively become Theresa May's number two in government, as the prime minister promoted him to first secretary of state as part of a post-general election reshuffle on Sunday (11 June).

Green, the 61-year-old former work and pensions secretary, has also become minister for the cabinet office. Alongside May, Defence Secretary Michael Fallon and Home Secretary Amber Rudd, Green was the face of the Tory "strong and stable" election campaign.

A long-term ally, he has known May since their time at the University of Oxford in the late in 1970s and both top Tories campaigned for a Remain vote at the EU referendum.

The prime minister's shake-up of her top team comes after Nick Timothy and Fiona Hill – May's joint chief-of-staffs – quit their posts after a cohort of senior Tory MPs urged May to sack the duo or face a leadership contest.

Gavin Barwell, the former housing minister who lost his London seat at the election, has inherited the role. The reshuffle come as the Conservatives continue talks with the Northern Irish Democratic Unionist Party (DUP) in a bid to continue to govern the UK as a minority government.

The Prime Minister has tonight spoken with the DUP to discuss finalising a confidence and supply deal when Parliament returns next week," a Downing Street spokesperson said on Sunday morning.

"We will welcome any such deal being agreed, as it will provide the stability and certainty the whole country requires as we embark on Brexit and beyond. As and when details are finalised both parties will put them forward."

Meanwhile, David Lidington, the ex-Europe minister, was promoted to Justice Secretary, with Liz Truss being demoted to chief secretary to the Treasury.

Elsewhere, there was not much movement in the cabinet as Foreign Secretary Boris Johnson, Chancellor Philip Hammond, Brexit Secretary David Davis, Health Secretary Jeremy Hunt, International Trade Secretary Liam Fox, Business Secretary Greg Clark and Fallon kept their posts.

May is also planning to meet with Graham Brady, the chairman of the 1922 Committee of backbench Conservative MPs, on Monday. Johnson, meanwhile, has urged Tory MPs to rally around the prime minister as Brexit negotiations with Brussels loom.

"Folks, we need to calm down and get behind the Prime Minister," he said in a leaked WhatsApp message published by ITV News. The latest opinion poll from Survation, of more than 1,000 people on 10 June, put Labour on 45% (+5) and the Conservatives on 39% (-3).

General Election 2017: results