The mother of an Oxford man left with brain damage after being stabbed in the head said he is showing signs of improvement, as his attacker failed to overturn his conviction.

Leonard Morrison, 38, known as Goldteeth, this week failed to have his conviction for the attempted murder of Samuel Marriott-Gray, in Blackbird Leys quashed.

The attack left the 21-year-old with permanent brain damage.

Last night his mother, Sonia McCarthy, welcomed the Appeal Court's decision and added that the family remained optimistic his condition would improve.

A trial at Oxford Crown Court last year heard Morrison thrust a 10cm knife into Mr Marriott-Gray's head up to the hilt, piercing his brain, after an argument about entry to a house party in Pegasus Road in August 2006.

Three judges refused a retrial for Morrison, of Bath Street, St Clement's, saying there was clear evidence he was the attacker.

Ms McCarthy said: "Although Samuel is not dead it's still a loss. My son will never be the same again. What this man has done to me is take away my son and whatever sentence he gets won't bring Samuel back to the way he was.

"We're trying to get on with our lives. But we haven't left Samuel out of our life. I still think there's hope and I'm sure he has gradually been getting better.

"I have to remain optimistic and thank God he is still with us.

"I'm pleased with the court's decision and didn't expect anything else.

"The evidence at the trial was so overwhelming it just could not be anybody else."

Mr Marriott-Gray remains in hospital with brain damage. He is visited daily by friends and family. But doctors have warned them he may never recover.

Ms McCarthy said her son still cannot speak or walk but can now move his eyes and wave his arms.

Last March at Oxford Crown Court, Judge Julian Hall sentenced Morrison to life imprisonment, with a minimum term of nine years, after he was convicted of attempted murder.

Morrison, an immigration overstayer, told the trial he was not involved in the violence but moving away from the trouble when Mr Marriott-Gray was stabbed.

At the Appeal Court hearing on Wednesday, Morrison's barrister, Judy Khan, claimed that Judge Hall's directions to the jury over Morrison's silence in a police interview rendered the conviction unsafe.

But Mr Justice Irwin refused the application for a retrial, saying that Morrison's silence was not an important issue at his trial.

He added: "In our judgment, the real issue for the jury was whether or not they accepted the evidence of the eyewitness."

Just one in six people convicted of carrying a knife in the Thames Valley are sent to jail, according to Ministry of Justice figures.

In 2006, 177 people were found guilty of possessing a blade in a public place, but only 28 were jailed.