A senior civil servant has launched an attack on Sir Philip Rutnam, the Home Office’s former top official, for “declaring war” on Priti Patel, accusing him of having “undermined the integrity” of his profession.

In an interview with The Telegraph, the mandarin said they had witnessed officials openly undermining Ms Patel in meetings, having apparently “disagreed with what she was trying to do”.

The official witnessed the minister becoming “frustrated” but said they never witnessed “bullying”. The senior Whitehall figure, who has served under both Labour and Conservative governments, said the “normal process” in Whitehall would have seen Sir Philip take a new role if he and Ms Patel could not work together.

Speaking on condition of anonymity, the official said: “He should have been saying, ‘you’re the democratically elected Home Secretary and it’s me who’s got to go.’ I think it sets a dangerous precedent – senior civil servants trying to take down a democratically elected minister. Even if her behaviour was bad you just do not do this.”

The extraordinary intervention from a serving mandarin comes after Sir Philip resigned last weekend with a broadside against Ms Patel, alleging “shouting and swearing, belittling people, making unreasonable and repeated demands”.