One FCDO civil servant described a cumbersome and time-consuming legacy IT system, where sharing documents online was impossible and staff relied on borrowing each other’s logins to access information when they were not otherwise in use. It meant there was a “resource of people that physically can’t be used” because they couldn’t access the system. “It slowed the whole thing down,” the civil servant said.

However, he took issue with Mr Marshall’s criticism of the shift system and working from home culture within Whitehall. In written evidence, Mr Marshall said: “Despite the urgency of the situation, the default expectation remained that FCDO staff would only work eight hours a day, five days a week.” He added that there was a lack of night shifts, and if any were allocated they were “extremely token”.

“Even putting aside the enormous urgency of the situation, given that Afghanistan time was then 3.5 hours ahead of UK time, this is extremely difficult to justify.”

He said that “staffing shortages were exacerbated by some staff working from home, which hampered communication”.

The civil servant did defend his department’s set eight-hour shifts because the working patterns constantly changed. He added that “there weren’t gaps in the rota and rostering system, it was more that there just still weren’t enough people given the state and the scale of the crisis.”

He added that while up to 100 people could work in the centre, there were other people working on the operation in different sections of the building simultaneously, who did not “need to be physically in the actual crisis centre”.

‘Symptomatic of the inertia’

“And then the reality is that a lot of it can be done from home,” he said.

“It’s more the decision making and the sensitive kind of work that needs to be done in the office. But if you’re just dealing with correspondence and letters, there’s not always necessarily a need to be in the office to do that.”

A defence source accused the FCDO of having been living in “dreamland” throughout the evacuation process, and cited a perceived lack of urgency around the booking of chartered flights out of Afghanistan for British citizens.

Upon hearing Mr Marshall’s allegations, one senior officer who worked on Operation Pitting on the ground in Kabul told The Telegraph that the working from home culture and set, eight hour shifts were “symptomatic of much of the inertia in the civil service”.

“I would say the FCDO staff in-country were very good, hard working and willing to do their best in completely unexpected conditions,” he said.

Speaking on Tuesday, Dominic Raab defended allegations that he took too long to make decisions, which the soldier said was a “fair” thing to do when it came to checking applications. However, he added that it resulted in “the military personnel having to make near instant decisions around who to let in or not”.