Sajid Javid told Boris Johnson he was a “puppet” of Dominic Cummings before he resigned as chancellor rather than accept a Cummings-led takeover of his Treasury, he has said in an interview about his experiences as a minister.

Speaking to the Institute for Government (IfG), Javid also said that his other departure from Johnson’s government, shortly before it collapsed in 2022, was because he had lost confidence in the prime minister after being assured that allegations about lockdown-breaking parties in No 10 were “bullshit”.

Asked to assess the three prime ministers he served under, Javid, who ran six different government departments in eight years, described Johnson as “the least well briefed”, compared with David Cameron and Theresa May.

In his first resignation under Johnson, in February 2020, Javid quit after being told by Johnson that he would have to fire his team of Treasury special advisers, known as spads, and work with new advisers selected by Cummings, Johnson’s chief adviser.

“I found that unacceptable – both firing my spads and then also how they would be replaced, because I thought I’d just be chancellor in name anyway,” Javid told the IfG as part of their ongoing series of discussions with former ministers.

“I just thought, I’m not going to be chancellor in name only. I’m not going to be a puppet,” Javid continued.

“I did say to the prime minister at the time, ‘You realise you’re the actual puppet here, right? Dominic Cummings is running rings around you, and you can’t even see it.’ At the time, he couldn’t see it. He denied it and said ‘That’s not the case. You don’t understand him. You’ve got him wrong. You guys should become friends and this and that’.”

Javid returned as health secretary in 2021 after the resignation of Matt Hancock, but resigned again a year later, on the same day as Rishi Sunak, Johnson’s then-chancellor, as Johnson’s administration collapsed around him.

“I just got to the point where I lost confidence in him as a prime minister, because there were so many other things going on,” Javid recalled.

“For example, I was told categorically by people – I won’t say who, but people very, very close to him – that there was no partygate, nothing happened, that this thing was bullshit.

“But it all turned out to be true and I felt I was misled a lot. I thought, if the centre, broadly speaking led by one man, is so willing to mislead his cabinet ministers, then you can’t function.”

Javid, who served as an MP from 2010 until stepping down last year, got his first ministerial job under Cameron, and also served in May’s cabinet.

Of the three, Javid said, Cameron was “the most effective”, contrasting this with May, whom he called well-briefed but indecisive, saying: “She would let her ministers argue with each other and still not come to a decision. Johnson was probably the least well briefed and probably of the three took the least interest in most things.”

In wider reflections on the pressures of a ministerial job, Javid said he had to remind his staff to allow time in his day to travel between meetings, and to have the time to eat.

“You would have a whole trip visiting hospitals or visiting police stations but there would be no provision at all. You actually need to eat. I don’t even mind if they got me a sandwich from a shop and gave it to me in the car when I’m driving to a meeting. But the point was, no one had thought about that,” he said.

Then suddenly I would say ‘Can I get something to eat?’ and they would say, ‘Oh, we haven’t got that on schedule’. A well-nourished minister is probably a better-performing minister.”