A ‘predatory manipulative sexual offender’ could be allowed to have his say on how the country is run while he is in jail, if Government plans are given the green light.

Alan Stephenson, of Broadway, Rodbourne Cheney, Swindon, was jailed for three years and eight months last February for having sex with a vulnerable 14-year-old girl.

North Wiltshire MP James Gray his hit out at the proposals, which would allow prisoners serving less than four years to vote, saying it was wholly offensive more than 2,000 sex offenders, such as Stephenson, would be able to have their say.

During his trial, Swindon Crown Court heard that Stephenson lived with his partner and their two-year-old son and had two older children from a previous relationship.

His victim, who had mild learning difficulties as well as behavioural problems, knew his partner and would sometimes help her with the child. When the police were investigating an unrelated matter in October 2008, they were told the 14-year-old was in a relationship with Stephenson.

Initially the girl denied anything was going on but then said they had cuddled and were going out before admitting they had had full sex.

Stephenson was arrested and confessed all to detectives.

He admitted having sex with the girl eight times including in her own home, when her parents were out, as well as at his house.

Mr Gray said “any sensible person” would think it outrageous the plans would see tens of thousands of criminals allowed to vote.

Speaking in the Commons, he said: “If as Government proposes prisoners serving less than four years are given the right to vote it would mean the vote would be given to 6,000 violent offenders, 2,000 sex offenders, 6,500 robbers and burglars and 4,500 drug offenders which I think any sensible person, including the Prime Minister I would think, would find wholly offensive and unacceptable.

“It should not be the European Court of Human Rights (ECHR) that decides this matter but this Parliament and will the secretary of state not listen instead to other countries in Europe, for example Belgium where prisoners serving up to four months can vote.

“Let’s make it four months, even better four days or even better than that, four minutes.”

Prisoners lost the right to vote in 1870 but, five years ago, prisoner John Hirst, who was jailed for 15 years for manslaughter, argued in the ECHR that he should be allowed to vote. The ECHR found that it was illegal for ministers to deny voting rights to all prisoners.

The Government was warned last year its failure to comply with the ECHR ruling risked sparking many more compensation claims and subsequently the coalition said it now planned to give voting rights to nearly 30,000 inmates serving less than four years.

Justice Secretary Ken Clarke said he accepted the proposals were not popular but said more trouble could be caused if the ruling was ignored.

"We are in government I am afraid, which I often say to my Lib Dem colleagues, and we have to act responsibly whatever our inner feeling about the wisdom of the decision that has been reached in the court whose jurisdiction we still accept,” said Mr Clarke.

Prisoners will vote by proxy. Judges would be given the discretion to withdraw voting rights when passing sentence in cases they deemed appropriate in a move designed to stop those jailed for serious offences but serving less than four years voting.