A Government minister is set for a court battle with a war veteran constituent who claims she has failed in her duty to represent him properly in a fight for compensation.
Ann Keen, the Labour MP for Brentford and Isleworth in west London, is being sued by John Taylor in what is thought to be the first such case of its kind.
But a spokesman said it was "nonsense" to suggest she had been lazy, insisting she made many representations on Mr Taylor's behalf but was unable to secure him a payout.
Mr Taylor has led a decade-long campaign for compensation after being exonerated of a theft for which he served three years in prison in the 1960s.
"I haven't asked for the Earth. I just want some assistance from my elected representative," he told the Daily Mail.
"But she is a disastrous and lazy politician who has failed to carry out her job."
A spokesman for Mrs Keen, a junior health minister, said there was "no substance" to his case which she hoped would come to court as quickly as possible.
"It's nonsense. It is not laziness. She was unsuccessful in securing compensation for him but that does not mean she did not try. She did, consistently," he said.
"Over a period of a number of years until 2005, she made representations on his behalf to the Home Office and various other people. She then advised him that, in the absence of any new evidence, she would not be able to make any further representations."
Mr Taylor had proved "persistent" however, he said.
"He persisted with his correspondence. He is a fairly persistent person who is very focused on his individual circumstances."
Brentford County Court "rather bizarrely" initially found against Mrs Keen when she failed to turn up for a hearing, the spokesman said.
But after being told that she had not received any correspondence from the court, that decision was reversed and Mr Taylor was instructed to come up with the evidence to prove his case that she was guilty of a "breach of her Parliamentary and statutory obligations to him".
The House of Commons code of conduct gives MPs a "general duty to act in the interests of the nation as a whole and a special duty to their constituents" but they have no legal obligations.
The spokesman said they had asked the court to bring the hearing forward as quickly as possible "so this case can be struck off and we can all move on".