The Northern Ireland secretary Karen Bradley has been sacked by the new prime minister, Boris Johnson.
Mrs Bradley had been in the post since January 2018. She is one of a host of big cabinet names to go.
In a statement she said it had been "an enormous privilege to... represent this special nation and integral part of our precious union".
"I personally regret that I will not conclude the current talks process," she added.
Mrs Bradley has been an MP since 2010, representing Staffordshire Moorlands.
She was secretary of state for digital, culture, media and sport before moving to the Northern Ireland Office.
One of Theresa May's closest allies, she remained faithful to the former PM.
In her statement she paid tribute to Mrs May for her "continued support and commitment to ensuring the unique needs of Northern Ireland were met and respected in full".
In her 19 months as secretary of state she came under heavy criticism.
During her time in the job there has been no progress on restoring the Northern Ireland executive, despite numerous talks.
Mrs Bradley often refused to take questions from the media on those talks.
She was accused of using delaying tactics to stall legislation to compensate victims of institutional abuse by victims' groups.
She was also accused of having a limited understanding of Northern Ireland, after admitting she did not know nationalists did not vote for unionist parties or vice-versa in elections when she took the job.
In March there were calls for her to resign over comments she made about the Troubles.
Karen Bradley said that killings at the hands of the security forces were "not crimes".
She later clarified that "where there is evidence of wrongdoing, it should always be investigated".
"I know how raw that pain is and I'm devastated to think that I have made it worse," she added.
In her statement on Thursday she paid tribute to the "strength and dignity" of Troubles survivors.
She praised the "heroism and courage displayed by the armed forces and the police in upholding the democracy and the rule of law",
In a day of many changes, important to recognise the determined efforts which Karen Bradley made to seek a restoration of devolution in NI. Whether city deals or broadband, Karen worked to ensure money secured through c&s reached people in NI.— Arlene Foster (@DUPleader) July 24, 2019
The former secretary of state said she was "immensely proud" at securing two City Deals for Belfast and Londonderry.
In March Mrs Bradley signed the terms on the Belfast City Deal, the first such deal in Northern Ireland.
It proposes to invest £350m into the Belfast region over the next 15 years.
The funding aims to support and encourage economic development.
'Decent and honourable'
DUP Deputy Leader Nigel Dodds, whose party props up the Conservatives in government, said the sacking was "no great surprise" given the extent of the cabinet clear out.
"I always got on well with Karen. She is a decent and honourable lady," he said.
"Clearly there were things we disagreed on like the backstop.
"There were things we felt she could have done in terms of Westminster action on Northern Ireland.
"But I wish her well for the future."
Alliance Party Leader Naomi Long said Mrs Bradley had been "doing the job with one arm tied behind her back due to Theresa May's coalition with the DUP".
She said she thought the new secretary of state would be put in the same position.