A home Office bill permitting members of the Oireachtas to sit at Stormont or Westminster was condemned in the Commons last night as a concession too far to Sinn Fein.
But despite their "deep unease" at the implications of the Disqualification Bill, Ms Ann Widdecombe, the shadow home secretary opened a two-day debate by confirming that the Tories would not be opposing the legislation at its second reading stage. The bill subsequently received its second reading by 300 votes to 17.
However, the shadow Northern Ireland secretary, Mr Andrew Mackay, has tabled an amendment, due to be debated later today, which would effectively defer implementation of the "dual mandate" proposal until there had been a start to IRA decommissioning.
Ms Widdecombe insisted the government give a cast-iron guarantee that the bill did not represent a move towards changing the oath of allegiance to Queen Elizabeth sworn by all MPs.
The Home Office Minister, Mr Mike O'Brien, said the legislation had no implications for the oath, but was designed to end an anomaly at a time of closer links between Britain and the Republic.
However, the Ulster Unionist MP, Mr Ken Maginnis, said the bill was a concession to be enamelled to the side of the Belfast Agreement, exclusively to facilitate Sinn Fein.
And a former Northern Ireland minister, Mr Michael Mates, warned that the bill could result in major conflicts of loyalty.
"By changing this you will allow people to join two different sovereign parliaments with two different aims in mind, and therefore there is a major conflict of loyalty," he said.
However, Mr O'Brien said it was possible for a member of a legislature in Brunei or Bangladesh to be a member of the Commons. The bill would put members of the Irish legislature wishing to sit in the Assembly or Commons in the same position as members of the legislatures of Commonwealth countries.
This brought opposition from a senior Labour backbencher, Mrs Gwyneth Dunwoody, who said the implications of the bill were more wide-ranging than the minister had suggested.
"I do have to ask whether this will not be used as a precedent for other non-Commonwealth countries," she said, adding that the legislation "if well intentioned" was "certainly ill researched." The oath of allegiance was to the head of the British state, she said, and that had to be borne in mind.
And a former home secretary, Mr Michael Howard , said the bill was wrong in principle. He did not understand how it was possible to stay loyal to the oath of allegiance and serve in another parliament at the same time.