Senior Tory backbencher Mr Andrew Hunter today announced that he was quitting the party to stand for the Northern Ireland Assembly as a member of Dr Ian Paisley's Democratic Unionist Party.
In a letter to Conservative leader Mr Iain Duncan Smith, the Basingstoke MP said that he would be quit Westminster at the next general election.
He said: "As you know, I have a long-standing and deep interest in the affairs of Northern Ireland. It has been suggested that I stand for the Northern Ireland Assembly in the elections next May as a DUP candidate".
The MP, who has sat at Westminster since 1983, said that he would become an independent Conservative for the remainder of this Parliament, as under the Tory Party constitution he would be unable to stand for Stormont.
"I wish to assure you that in practice this will make little difference. I remain one of your most loyal supporters and I shall continue to support you in the House of Commons," Mr Hunter added.
The MP sat on the Commons' Northern Ireland Affairs Committee between 1994 and 2001. He added that his wife Jan's poor health from cancer was a further reason for standing down.
The couple are planning to return to Northern Ireland and repurchase part of their old family farm in CoDerry.
DUP deputy leader Mr Peter Robinson confirmed Mr Hunter was seeking his party's nomination to run for an Assembly seat in Lagan Valley.
He added: "Andrew will be a terrific addition to our team. I think it is a measure of the man that he could have remained for many years an MP in Basingstoke but he feels so strongly about Northern Ireland that he is prepared to contest an election here because of what has happened since the Anglo Irish Agreement".
PA