Grant Shapps has been announced as the UK’s new defence secretary, as the prime minister carries out a mini-reshuffle at the top of government.

The appointment comes after Ben Wallace revealed last month he would be leaving the role the next time Rishi Sunak made changes to his cabinet – as well as stepping down as an MP at the next election.

Mr Shapps had been serving as the energy security and net zero secretary before his promotion to the Ministry of Defence.

The new post will be his fifth cabinet position in a year – having been transport secretary under Boris Johnson, undertaking a brief stint as home secretary under Liz Truss, before being appointed business secretary when Mr Sunak first took office.

Minister for children, Claire Coutinho, will take over the energy security brief – the first cabinet post for the MP who was only elected in 2019 – and her Conservative colleague David Johnston will fill her former post at the Department for Education.

Sky News’ deputy political editor Sam Coates said both Mr Shapps and Ms Coutinho were “loyalists”, adding they had been chosen by the prime minister “not just perhaps because of their skills, but because they have stuck by Rishi Sunak”.

The new defence secretary wrote on X, formerly known as Twitter, that he was “honoured”, and he paid tribute to his predecessor’s “enormous contribution… to UK defence and global security”.

Mr Shapps added: “As I get to work… I am looking forward to working with the brave men and women of our Armed Forces who defend our nation’s security. And continuing the UK’s support for Ukraine in their fight against Putin’s barbaric invasion.”

He garnered the support of some of his colleagues, with Conservative Leader of the Commons Penny Mordaunt saying he would do “a great job”.

But the new hire has already attracted criticism from opposition parties, with Liberal Democrat defence spokesperson Richard Foord saying: “At a time when the Armed Forces need someone to stand up for them, Rishi Sunak has appointed a yes-man.

“The Conservative government merry-go-round has to stop. They have taken the Armed Forces for granted for too long, and we are all left less safe as a result.”

Labour’s shadow defence secretary John Healey congratulated his new opposite number on X, formerly known as Twitter, but added: “After 13 years of Tory defence failures, a change at the top will not change this record.”

His colleague, shadow attorney general Emily Thornberry, also told reporters: “It really doesn’t matter how many new jobs Rishi Sunak gives to his friends. It’s still just moving the deckchairs, they are still a sinking ship.

“This country really needs change and the only change we are going to get is if we get a Labour government.”

Doubts have also been voiced from the sector itself, with former chief of the general staff of the British Army, Lord Dannatt, telling Sky News that Mr Shapps knew “very little” about defence.

He said Mr Wallace “did a good job, but he leaves with work in progress”, adding: “Now we have a new defence secretary who knows very little about defence, and it’s a complex portfolio. It will take him quite some time to get up to speed.”

Lord Dannatt continued: “Although he may well have been appointed as someone who is going to support the prime minister and help the Conservative Party in its general election campaign, [defence chiefs] will be hoping that he will really understand defence and push the case for defence, not just for the Ministry of Defence’s own benefit, but for the benefit of the whole country.”