Defence secretary Ben Wallace has revealed he will step down from his post at the next reshuffle and quit as an MP at the next election.
Mr Wallace, the longest-serving Conservative to head the Ministry of Defence, said in an interview with The Times: “I’m not standing next time.”
He added that he will not force a by-election by resigning “prematurely” – as fellow allies of Boris Johnson have done.
Mr Wallace further confirmed he would leave the cabinet at the next reshuffle, which the prime minister is expected to hold this September.
Sky News reported that he was considering the move on Saturday.
“I went into politics in the Scottish parliament in 1999. That’s 24 years. I’ve spent well over seven years with three phones by my bed,” he told The Times.
When asked what the devices were for, he replied: “Secret, secret and secret.”
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It comes following controversy last week when the defence secretary told a NATO summit press conference that the UK was not an “Amazon” delivery service for weapons to Ukraine.
He also said Kyiv might be wise to let its supporters “see gratitude”.
Prime Minister Rishi Sunak later pushed back against the comments, saying Ukraine’s President Volodymyr Zelenskyy had “expressed his gratitude for what we’ve done on a number of occasions”.
Mr Zelenskyy, speaking at the same event in Lithuania, also responded: “I believe that we were always grateful to the UK.”
Following the news of his departure on Saturday evening, Mr Wallace took to Twitter in an attempt to clarify his “Amazon” comments.
In a series of tweets posted in Ukrainian, he said his remarks were “somewhat misinterpreted”.
“I said that Ukraine sometimes needs to realise that in many countries and in some parliaments there is not such strong support as in Great Britain,” he wrote.
“It was a comment not about governments, but more about citizens and members of parliaments.”
He added that he meant to say Britain’s relationship with Ukraine is not “transactional” but more of a “partnership”.
Speculation about the defence secretary’s fate has been mounting for weeks, with officials inside the Ministry of Defence wondering who might replace him.
It also comes following a failed UK bid to make Mr Wallace the next head of NATO.
The 53-year-old last month ruled himself out of the race to replace Jens Stoltenberg after apparently failing to get the backing of the US.
Mr Wallace told The Times that a desire to spend more time with his family, including his three children, was one of his reasons for leaving politics.
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Asked what he would do next, he replied: “I’m quite happy to go and work at a bar,” or “just do something completely different.”
Wallace’s career in the corridors of power came after he left school at the age of eighteen – before a “short stint” as a ski instructor in Austria.
He then served as a captain in the Scots Guards and worked in the aerospace industry before entering politics in 1999.
Mr Wallace was once tipped as a potential candidate for Tory leader and prime minister.
But he ruled himself out of the race to replace Boris Johnson last summer and instead backed eventual winner Liz Truss.
He then said he would not stand in the contest to replace her and revealed he was “leaning towards” backing a return by Mr Johnson to the post.
Mr Wallace had been facing the prospect of effectively losing his constituency of Wyre and Preston North at the next general election under boundary changes – meaning he would have needed to stand in another seat to remain as an MP.
The MP also revealed in his interview with The Times that, on the eve of the war in Ukraine, he discussed Britain supplying weapons to Kyiv – using whiskies as a code.
Referring to secret talks with his counterpart Oleksii Reznikov, he said: “the Nlaw [anti-tank missile] was Glenfiddich and Harpoon anti-ship missiles were Islay.
“I would text him saying ‘I’ve got some whisky for you’ or ‘the whisky is on its way’. We just picked codewords, minister to minister.”