Former Home Secretary Amber Rudd was let down by her own officials, an inquiry into the events leading up to her resignation has concluded.
Ms Rudd quit the role in April, saying she had “inadvertently misled” MPs investigating the Windrush scandal.
A report out later says she was “not supported as she should have been”.
It says Ms Rudd lost confidence in her officials to such an extent she prepared for a later parliamentary appearance on her own.
The report’s author, the prime minister’s advisor on ministers’ interests, Sir Alex Allan, describes this decision as “dangerous”.
The Windrush controversy began when it emerged that some migrants from Commonwealth countries, who were encouraged to settle in the UK from the late 1940s to 1973, were being wrongly declared illegal immigrants.
Ms Rudd came under fire for the government’s treatment of these residents – known as the Windrush generation – and their relatives and the wider impact of its “hostile environment” policy designed to deter illegal immigration.
When she addressed MPs on the home affairs select committee on 25 April, Ms Rudd gave an inaccurate assertion that her department had no targets for immigration removals.
She blamed officials, and the report – written in May – describes a series of confused email exchanges and crossed wires.
Ms Rudd later admitted “local” targets for voluntary removals had been set but told the Commons she had not been aware of them. This was subsequently contradicted by a June 2017 memo from an official, copied to Ms Rudd, that referred to targets.
While Sir Alex does not recommend any civil servant face a misconduct investigation, he singles out for criticism the then director general for immigration enforcement Hugh Ind, who has since moved to a different civil service role.
The report said he had offered a “less than satisfactory performance”.
Speaking to the BBC last month about her career, Hastings and Rye MP Ms Rudd said she been misled by some civil servants about immigration enforcement.
Ms Rudd told Nick Robinson’s Political Thinking podcast she should have done more to find out what was happening but when she started “really probing… it became evident that [officials] didn’t know what was going on.”
She said it had made her more sceptical about civil servants – although she praised those she worked with on counter-terrorism as “fantastic”.
She added she would “quite like” to be home secretary again “because there’s a few things I’d like to do a bit better than last time”.