A paranoid schizophrenic who knifed a great-grandfather to death has been jailed for life with a minimum of ten years.

Matthew Daley, 35, stabbed Don Lock repeatedly on the side of the road on July 16 last year, leaving 35 stab wounds.

He attacked the retired solicitor, 79, on the A24 near Findon after a shunt between their cars.

Daley admitted killing Mr Lock but was cleared of murder after a trial in May when the jury accepted his defence of diminished responsibility due to his mental health problems.

Sentencing this afternoon at Lewes Crown Court, Justice Singh said the jury must have been sure that the level of violence Daley used was "unreasonable", even given his delusion that Mr Lock was a threat.

He said: "It is clear that any suggestion of lawful self defence was rejected, otherwise there would have been a complete acquittal."

He added: "I must be loyal to the jury's verdict in this case. It's clear from the verdict that the defendant's responsibility for the homicide in this case was substantially impaired.

"It does not follow that it was completely extinguished."

Daley will start his sentence in mental health hospital and then be moved to prison for the remainder of his sentence if he is deemed fit to leave hospital.

Mr Lock's son, Andrew Lock, read a statement to the court this morning from his family, describing their grief and trauma at their loss.

He said: "The last ten months have been extremely difficult for our family and the final verdict means some justice for dad - never enough and nothing that will bring him back to us.

"Our memories of the night of July 16 are still as clear as if it happened yesterday and not a day goes by without thoughts of that night or thoughts of dad. It is heartbreaking.

"It is the most overwhelming pain you could ever imagine and it catches you by surprise continuously - you can be talking and laughing one minute and then break down in tears the next with all that pain rushing back as strong as ever. We would not wish what we have been through on our worst enemy.

"Dad was a wonderful husband to mum for 55 years and a wonderful father for over 50 of them. Last week would have seen Dad celebrate his eightieth birthday for which mum had already planned a big party."

More than 1,000 people attended Mr Lock's funeral in his home town of Worthing last year. Last week would have been his 80th birthday.

Today the court heard that before the trial started Daley had "expressed his remorse in a letter to the Lock family."

Defending, David Howker QC also highlighted the accepted failings in Daley's mental health treatment in the years before the killing by the Sussex Partnership NHS Foundation Trust.

During the trial the court was read a letter of apology to Daley's family from the trust's chief executive, Colm Donaghy.

Mr Howker said today: "We will submit that were it not to some extent for that failing, he (Daley) probably would not be here today."

He said Daley's offending was "solely confined" to his treatable mental illness and he was otherwise a "gentle man" obsessed with taking care of his horses and goats.

Wearing a grey shirt and black jeans, Daley, formerly of St Elmo Road, Worthing, spoke only to confirm his name.

The court heard he is being held at a medium secure hospital.