Southend West MP David Amess has vowed to continue fighting to clear his son's name after an appeal against his conviction for assault was lost.

David Amess Jnr won a cut in his prison sentence from four years to three but judges rejected claims that the conviction was "unsafe".

After the hearing, a statement from the Amess family said: "Some progress has been made in our endeavour to clear our son's name and to secure justice for him.That we intend to pursue with renewed vigour."

Tory MP Mr Amess, who is married with four other children, would not comment further.

David Amess Jnr, 21, of Crowstone Road, Southend, was jailed for wounding with intent to cause grievous bodily harm after hitting a man over the head with a champagne-style bottle in a club.

Judges at the Court of Appeal on Friday dismissed claims the trial judge had misdirected the jury during his summing up and Amess had not received a fair trial.Mr Justice Calvert-Smith said it appeared Amess had in fact been treated "more favourably" than he may have been.

His lawyers successfully argued the sentence was too long given that the wounds inflicted were minor. Amess had lashed out in the heat of the moment and the bottle did not break, they said.

Although pre-sentence reports had been unfavourable, Amess was deeply sorry for what had happened.

Mr Justice Calvert-Smith said it was worrying Amess viewed himself as a victim. However, in cutting the sentence he observed the injuries inflicted were not the most serious of their kind.

The court heard Amess attacked Paul Trussler, 29, from Leigh, in Talk nightclub, Southend.

A fight developed after Mr Trussler stepped on Amess's foot and he was struck over the head with the bottle, suffering a 4cm wound to his scalp that required stitches.

The appeal ruling means Amess will have to serve only half his sentence, rather than two-thirds, before he can apply for parole.