Getty ImagesMartin Hewitt with Sir Keir Starmer at a security summit last yearThe former police chief tasked with cutting the number of small boat crossings across the Channel is leaving the job just 18 months after being appointed by Sir Keir Starmer.
Martin Hewitt's appointment as the UK's Border Security Command had been presented as a "a significant step forward in the fight against illegal migration and criminal smuggling gangs".
However, he will now be replaced - with ministers working on interim arrangement before a permanent successor is appointed.
He will leave the job at the end of the month. Sources declined to say whether he had been sacked or had left voluntarily.
A Home Office spokesperson said: "We would like to thank Martin Hewitt CBE QPM for his dedicated leadership since the creation of the Border Security Command.
"Over the past 18 months, the Border Security Command has brought government agencies, law enforcement and international partners together to tackle people smuggling gangs, as well as seeing the Border Security, Asylum and Immigration Act into law."
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Despite the Labour government's promise to tackle the trafficking gangs behind the Channel crossings, the number of people entering the UK on small boats has continued apace while Hewitt was in the role.
Last year saw the second highest number of crossings for a calendar year.
Appearing before the Commons Home Affairs Select Committee in October last year, Hewitt expressed "frustration" at the length of time it was taking the French authorities to act to prevent the crossings.
He also said the process of deterring people from making the journey was "always going to take time".
Responding to his departure, the Conservative shadow home secretary Chris Philp said: "The government's complete failure on small boats isn't down to Martin Hewitt.
"It's because Keir Starmer and Shabana Mahmood are too weak to take the necessary action, such as coming out of the ECHR [European Court of Human Rights] and deporting all illegal immigrants within a week of arrival.
"Labour's decision to cancel the Rwanda removals plan was a disaster."
The previous Conservative government had sought to deter people from making the crossing by sending arrivals to Rwanda, where their asylum claim would be processed.
However, the scheme ran into legal difficulties and Labour scrapped the plan shortly after coming to power.
Hewitt was given the job after a career in policing, which included serving as chairman of the National Police Chiefs' Council.
When he was announced as head of Border Security Command, the prime minister praised his experience, saying: "No more gimmicks. This government will tackle the smuggling gangs who trade the lives of men, women and children across borders.
"Martin Hewitt's unique expertise will lead a new era of international enforcement to dismantle these networks, protect our shores and bring order to the asylum system."
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