Blow to David Cameron as only Ulster Unionist MP Lady Hermon quits party

David Cameron's alliance with the Ulster Unionists suffered a serious blow today when the party's only MP resigned and promised to stand as an independent in her North Down constituency.

Lady Hermon announced this morning that she would contest the seat she is favourite to hold – but not as an Ulster Unionist.

She will stand against the joint UUP-Conservative candidate Ian Parsley, who the party had already lined up in anticipation of Hermon's move, in one of the most affluent constituencies in Northern Ireland.

In a statement Hermon said she was leaving the party due to her refusal to support its pact with the Conservatives.

The North Down MP said the distance between herself and the UUP had become "so great" that she had decided to resign.

But she also said she would "stand her ground" and fight the seat as an independent.

Hermon, the Ulster Unionists' only MP, said she felt "profound sadness" at leaving the party.

In the House of Commons she has consistently supported Labour on issues including the detention of terrorist suspects for 28 days. If there is a hung parliament Hermon is expected to back Labour in the Commons.

Last October she boycotted her party's annual conference, which was attended by William Hague, the shadow foreign secretary. She was photographed walking her dog along the North Down shoreline while the UUP in Belfast feted Hague and the Tory pact.

A number of working-class UUP activists, such as former Belfast councillor Dr Chris McGimpsey and the unionist historian Roy Garland, have also openly opposed the alliance with the Tories.

Hermon has always been a natural Labour supporter and regards the link-up between the Tories and the UUP as detrimental to the party she once belonged to.

She is known to be concerned that proposed Tory plans for cuts in jobs and services will hurt the poorest sections of Northern Ireland.

Her former party leader Sir Reg Empey today expressed his "deep regret" over her decision to leave the party and standing against it in the forthcoming general election.

"I wish to thank her for her contribution to Ulster Unionism since her election in 2001. I believe that the values we share far outweigh the differences in approach to some issues.

"The party's major policy decisions have been reached after widespread consultation and have been unanimous. I wish Lady Sylvia and her family well in the future," Empey said.

The leader of the Democratic Unionist party, Northern Ireland first minister Peter Robinson, today said his UUP rivals had "run out of steam years ago".

"They have no plan or ideas for the future," said Robinson. "I see no evidence of any recovery in their electoral fortunes. They were too weak to take on Sinn Féin five years ago and are even weaker with their link to the Conservative party now. They are a party of the past and not of the future."

Robinson, who sits in the Northern Ireland assembly and the House of Commons, said he would be standing again as an MP at the next general election.

However the DUP leader pledged to end such "double-jobbing" among his colleagues, who will give up seats in the assembly if they are elected to the Commons.

The East Belfast MP said the prospect of a hung parliament meant it was important the party leader remained an MP.

"While personally I made no secret of the fact that I would have been content to concentrate on the assembly I understand the access that comes with being a member of parliament is important for the leader of unionism, whoever that is," he said.