Boris Johnson’s departure on holiday on Saturday, despite public warnings the Taliban would be in Kabul within hours, has been criticised as a “dereliction of duty” by former senior military and security figures. It emerged on Monday that the prime minister and the foreign secretary, Dominic Raab, took their summer holidays at the same time before both taking the decision to return. Johnson had gone to Somerset, and Raab was in Cyprus until Sunday, hours before the fall of Kabul, after being absent from public debate for more than a week. Major Gen Charlie Herbert, who undertook three tours of duty in Afghanistan between 2007-18, said: “It is almost impossible to believe that the prime minister departed on holiday on Saturday; he should hang his head in shame. It is dereliction of duty on an extraordinary scale. “He is overseeing one of the greatest military humiliations in the recent history of this country. Three weeks ago Gen Lord Dannatt and 44 other senior retired military officers wrote openly to the government to express their grave concern about the handling of the interpreter issue and urged the government to accelerate the relocations. “That they failed to heed the warning is symptomatic of the disastrous complacency that has led to this national humiliation. Interpreters will die as a result of their apathy.” Lord Ricketts, the former chair of the Joint Intelligence Committee (JIC), told the Guardian that Johnson’s holiday decision was “one more piece of evidence that Whitehall as a whole failed to anticipate either the scale or the speed of the collapse of the Afghan regime and the implications for British interest”. Adm Lord West, the former first sea lord and chief of the naval staff, said: “I would be extremely surprised and indeed appalled if the JIC and assessments staffs were not predicting a very rapid collapse of the Afghan regime in the face of Taliban pressure by Saturday. “In view of that I find the prime minister’s decision to go on holiday surprising. I also find the foreign secretary’s absence baffling. Holidays are important but not crucial. World events have a remarkable habit of happening in August and the government needs to be capable of responding quickly.” Johnson returned from Somerset and chaired his second Cobra meeting on Afghanistan in three days on Sunday afternoon, as well as speaking to Nato’s secretary general, Jens Stoltenberg, and the UN secretary general, António Guterres, about the Taliban takeover. No 10 said he would remain working in Downing Street until at least Wednesday, when parliament will be recalled. “The prime minister has returned to Downing Street today,” his spokesperson said. “He has been monitoring the situation in Afghanistan throughout.” No 10 also said Raab had attended meetings while away and spoken to ambassadors and senior staff. Johnson’s spokesperson said the Taliban “have moved swiftly across the country, but we’ve monitored the situation throughout and have been focused on getting out those Afghan nationals who’ve been working with the British and obviously the British nationals themselves”. The Labour leader, Keir Starmer, said there had been a “catastrophic miscalculation” over the strength of the Taliban and the resilience of Afghan forces. Starmer said Raab should have returned sooner from his holiday, and described the speed of the government’s response to the situation in Afghanistan as slow. Asked whether he should have returned from holiday sooner to deal with the crisis, Raab said: “As we’ve just described, everyone was caught by surprise by the pace and the scale of the Taliban takeover. “I think the important thing to understand is right the way through last week … I’ve been directly in touch with my team, directing them, which has paid the dividends. You can see what we’ve delivered with 150 British nationals who are going to be arriving back in the UK tomorrow [Tuesday] morning.”