Wantage MP Robert Jackson, who defected from the Tories to Labour in January, is breaking a "solemn promise" not to campaign in the constituency, according to his political rival.

So far, Mr Jackson has not canvassed support for Mark McDonald, Labour's prospective parliamentary candidate for the Wantage constituency.

But on April 9 he is actively supporting Mr McDonald for the first time in the constituency by joining him for a walkabout in Didcot. Mr Jackson is standing down at the General Election next month after representing the constituency since 1983.

Ed Vaizey, the Conservative Party's prospective parliamentary candidate for Wantage, said he felt let down by Mr Jackson, who had assured him he would not campaign against him.

Mr Vaizey said: "He has broken his promise -- he made a solemn promise to me that he would not canvass in the Wantage constituency as a member of the Labour Party. His presence on the streets will, I suspect, actually gain more votes for the Conservatives than for Labour and will not detract from my three-year campaign to represent this wonderful constituency."

Mr Jackson said he originally intended to avoid "conflict" in the election campaign but felt no obligation to stand back after Melinda Tilley, leader of the Conservative group on the district council and vice-chairman of the constituency association, provoked a row.

Mr Jackson reported Mrs Tilley to the Standards Board following comments she made in the Oxford Mail regarding a Tory Party agent who worked for Mr Jackson, but it decided not to take up the case. Mr Jackson has consulted lawyers regarding Mrs Tilley's comments.

Mr Jackson said: "She misrepresented factually what had occurred, refused to apologise and there was no clarification from the Wantage Conservatives of what they knew to be the facts.

"When I switched parties I said my intention was to avoid conflict, but I was plunged into a row by Melinda Tilley.

"It is perfectly logical that having joined the Labour Party I am now supporting it. I hoped to be able to manage my detachment from the local Conservatives in a civilised manner, but that has not been possible.

"I made no solemn pledges, promises or commitments not to canvass in the constituency and it would have been absurd to have done so."

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