Boris Johnson has authorised a “compensation” payment of almost £250,000 to the outgoing cabinet secretary, Sir Mark Sedwill, after he agreed to step down, it has emerged. The government made public a letter from the prime minister to the permanent secretary of the cabinet office, Alex Chisholm, approving the payment, which is likely to be put into Sedwill’s pension pot. In the letter Johnson says Chisholm had advised that, “in consideration of his employment position, and in the circumstances of his role being split, and Sir Mark stepping down early, it would be appropriate to make a compensation payment of £248,189”, and that it would represent value for money. Details of the payout were released after Sedwill made his first public appearance since his departure was announced, complaining that senior officials like him had become “fair game” for hostile briefings in the media. Britain’s most powerful civil servant told the national security strategy select committee that being briefed against had become a “regrettable feature of modern politics” as he was asked why he had agreed to leave the heart of government. “I’m not the only official that’s happened to – indeed, some others have had it worse – but we appear to be in an era where some of us are fair game in the media and I’m afraid it goes with the territory now. I guess my successor will have to deal with some of that as well,” Sedwill told the committee of MPs and peers. Johnson announced that Sedwill would stand down at the end of last month, ending weeks of speculation about the future of the cabinet secretary, who also holds the post of national security adviser. He had been accused by Downing Street sources in March of failing to get to grips with the coronavirus crisis, and was said to have fallen out with Johnson and his chief aide, Dominic Cummings, over the handling of the pandemic. Reflecting on that experience, Sedwill told the committee it was “never pleasant to find oneself, particularly as an official, in the midst of stories of that kind” and added it was difficult to deal with “briefings to which you can’t really reply, particularly those that are off the record and sniping away”. The committee hearing into Sedwill’s work as national security adviser began when he was asked abruptly by the committee chair and former Labour foreign secretary Dame Margaret Beckett: “You have resigned. Why?” Sedwill said: “I haven’t resigned. The prime minister and I agreed I should step down, it was by agreement. And that was essentially because we had concluded that it was time to split the jobs.” He added: “As we move into this next phase of dealing with Covid recovery, we concluded we needed a separate national security adviser, a separate cabinet secretary, and those people should see the prime minister through the rest of this problem.” Sedwill will leave government in September and a competition is open to all past and present permanent secretaries to replace him as cabinet secretary. His job as national security adviser will be taken on by David Frost, in addition to his existing job as chief Brexit negotiator.