Grant Shapps has been chosen to replace Ben Wallace as defence secretary in a mini-reshuffle of the cabinet, prompting criticism from some Conservative MPs and former military figures about his lack of relevant experience. The move handed Shapps his fifth cabinet post in a year, with Claire Coutinho, the outgoing children’s minister and 2019-entrant MP, picked to take over as energy secretary. David Johnston, another MP elected at the last election, replaces Coutinho and will become the seventh children’s minister in the past four years, sparking further concerns about ministerial churn. A reorganisation of Rishi Sunak’s top team had been expected for weeks, given Wallace’s desire to step down. It was scaled down, insiders suggested, to avoid any fallout threatening to blight the Conservative party conference in October. Shapps was appointed on Thursday morning and within hours some Tory MPs and former service heads voiced concerns about his lack of first-hand exposure to foreign affairs, defence and security. Richard Dannatt, a former chief of the general staff of the British army and now a crossbench peer, told Sky News that while Wallace “understood defence well”, it would be a tricky brief for Shapps, who over the past 12 months has also served as transport secretary, home secretary – for a week under Liz Truss – and business secretary. “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 said. He later told BBC Radio 4 that “the big question” remained as to whether Shapps would put his loyalty to Sunak above pushing for the needs of the defence community. Mark Francois, a Conservative MP who is a member of the Commons defence committee, said Shapps faced a “very steep learning curve”, and many MPs had expected and wanted James Heappey, the junior defence minister, to be promoted. “Grant Shapps is a bright bloke but he’s going to have to come up to speed very, very quickly,” Francois told GB News. A former cabinet minister also privately said they were “completely underwhelmed” by Shapps and it was “baffling” for other serving and former defence ministers to have been passed over, given the war in Ukraine. In his first comments on taking the role, Shapps paid tribute to Wallace’s “enormous contribution” to UK defence and global security over the past four years. He added that he was “looking forward to working with the brave men and women of our armed forces who defend our nation’s security” and continuing to support Ukraine. Downing Street was reluctant to appoint a high-profile Tory with military experience to replace Wallace. Sources said they feared figures such as Penny Mordaunt and Tom Tugendhat, who have both served in the armed forces, “would use the job to campaign for the leadership” if Sunak lost the next election. One Whitehall insider, speaking on condition of anonymity, was sceptical about the choice of Shapps. “The MoD has a really serious challenge around making ends meet while having to transform to match a much more serious threat,” they said. “This will likely exacerbate the current drift towards the next election.” But another former senior security official, who worked with Shapps previously, described the new defence secretary as a seasoned character who remained “steady when things were hot”, and they emphasised that he would have to deal with many sensitive issues in his new job, often demanding a swift response to apparent aggression. Tory strategists suggested Shapps’s promotion as evidence that Sunak was stepping up planning for a general election campaign. They pointed to Shapps’s record of delivery and communication, as well as his being an “attack dog” who would take the fight to Labour. Shapps is a keen user of TikTok, which the government has banned on official devices. Tobias Ellwood, the chair of the defence select committee, said Shapps would get “the mother of all briefings” when he entered the Ministry of Defence on Thursday. “I suspect he might have his phone, not taken away from him, but certainly he’ll come out with less apps on his phone than when he walks in,” Ellwood added. New defence secretaries are briefed first about the Trident nuclear programme, its capabilities and the impact it can have, although decisions on using the weapons are ultimately for the prime minister. They are also told about their authority in terms of the use of force and, over a longer period, about possible threats from Russia, China, other hostile countries and international terrorism. During last summer’s Tory leadership race, Shapps briefly took a tilt at replacing Boris Johnson. However, he failed to muster enough support to make it on to the MPs’ ballot. In his pitch to Tory backbenchers, Shapps pushed for defence spending to rise to 3% of gross domestic product, saying: “Freedom is not free.” Nato recommends at least 2%, and Sunak has committed to 2.5% in the long term. Sunak had many run-ins with Wallace over defence spending, which the latter referred to in his resignation letter to the prime minister. Wallace wrote: “I know you agree with me that we must not return to the days where defence was viewed as a discretionary spend by government and savings were achieved by hollowing out.”