Tory leader David Cameron yesterday heralded as a 'breakthrough' the defection of two Oxford city councillors to the Conservative Party.

However, one of the councillors, Paul Sargent, reckoned he "had some convincing to do" of the local electorate to retain his seat.

A media scrum descended on the Town Hall yesterday as Mr Cameron, MP for Witney, met Mr Sargent and Tia MacGregor as they completed their move from the Liberal Democrats to Conservatives, via the Independent group - the first Tory representatives on the council since Barbara Burgess was elected in 2000. They now have a year in which to convince voters in their respective Carfax and Quarry & Risinghurst wards they should be re-elected.

After the Oxford Mail broke the news on our website - www.oxfordmail.net - some correspondents reacted angrily and called for the duo to quit and hold a by-election.

Mr Cameron rejected the calls. He said: "This is the first time the Conservative Party has had city councillors in Oxford for seven years - this is a real break- through. I hope this shows we are the party of the city as well as the town and the shires.

"If we can win in Witney, Bicester and Banbury we should be able to do it in Oxford."

Yesterday, when asked whether he could win his Carfax seat in May next year, Mr Sargent said: "I have got some convincing to do but I am pretty confident I can do it."

When Muslim mother-of-two Dr MacGregor, 39, quit the Lib Dems earlier this year she said the party "was no longer working for her".

And when Mr Sargent left in May 2006 he said "I still share many of the principles and policies of the Liberal Democrats, but sometimes you have to go in a different direction".

But John Bullivant, 84, of Leiden Road, Headington, said: "These councillors have got no respect for the people who elected them.

"Dr MacGregor has already let the people of Quarry & Risinghurst down once - there should be a by-election. They should not have been allowed to get away with it because they have a responsibility to those who elected them."

City council leader John Goddard added: "These councillors will have no credibility as Conservatives unless they resign now and stand in by-election."