Detectives are to meet with a potential witness in a 40-year-old case involving the mysterious death of a Welsh teenager amid a suggestion he may have been hit by a police car.
Peter Watts, 15, left his home in Colwyn Bay, North Wales, on the afternoon of January 18 1976, and was found fatally injured in the Euston Road underpass in London in the early hours of the following morning.
Despite repeated appeals over the past four decades, detectives have never been able to uncover the truth of what happened to him.
After the Metropolitan Police re-issued the appeal on Tuesday a man, who had been a newly qualified black cab driver at the time, came forward to say he remembers seeing someone hit by a police car in that location.
John Varney told ITV News: "The police car hit him and he went up in the air. He was half way across the road but then came back into the lane that I was in.
"So, I put my brakes on about six foot away from where he was laying on the road.
"Having seen the guy in my headlights he moved for a while and then his eyes were looking at me - and at the front of the cab and gradually his eyes just closed."
Mr Varney claimed he was then told by a police officer to leave the scene.
He said: "The police car reversed back and to the rear of me, I was about to get out the cab and one of the police officers got out the car and said to me 'Go!'"
Earlier Peter's brother Mark - his only surviving relative - said he had all but given up hope of finding out the truth about his brother's final hours.
He said: "It's quite probable somebody knows more about the last hours of my brother than I do. But they could have passed away. I don't think I'll ever find the truth now."
Scotland Yard confirmed the witness who has come forward has been spoken to by telephone and said officers will meet with him as soon as possible.
A spokesman said: "As a result of the press appeal, detectives have today, Tuesday, January 19, been contacted by a third party acting on behalf of an individual who has claimed to have new information regarding the death of Peter Watts.
"Officers have since spoken with the man by telephone and will be meeting with him at the earliest opportunity."
The spokesman added that any new information will be "vigorously investigated".
Mr Varney, who said he had never seen any publicity around the case before, told ITV News he had not come forward sooner as he assumed the police he said he saw at the scene would "take care of it".
On the Sunday afternoon that Peter left home for the last time, he told his parents he wanted to stay at the house rather than going for a drive with them and Mark.
He left a note for his parents saying he was planning to help a friend with homework, but is thought to have bought a ticket from Colwyn Bay to Chester and taken the 5.15pm Holyhead to London train.
The teenager failed to leave the train at Chester and it is believed that he travelled to Euston, arriving at 9.15pm.
Apart from the guard who sold Peter his train ticket at Colwyn Bay, there were no further confirmed sightings of the 15-year-old during the journey.
At around 1.30am the following day a taxi driver found Peter in the Euston Road underpass. He had injuries consistent with a fall, but nothing to suggest he had been pushed or involved in a road accident.
There was no evidence of any sexual assault, and his watch and glasses were missing. They have never been found.