There was something hauntingly familiar about the face John Renehan saw on television.

He was certain that it was his father, who had officially been found dead and was cremated five years ago.

Yet there before his eyes on the screen was his father, in a care home and the subject of an appeal on a show about missing people for anyone who knew him to come forward.

Emotional reunion: John Renehan, right, is demanding an apology from police for the trauma he suffered believing his dad John Delaney, left, was dead for the past five years

'I sat down in shock. I was sure it was him straight away,' said Mr Renehan, 42. 'You know when it's your father. We look the same and have the same characteristics. It was like looking in the mirror.'

He contacted police and four weeks later DNA tests confirmed that the man he saw on the TV screen is indeed his father John Delaney, now 71.

Father and son have had an emotional reunion and an inquiry is under way to establish the identity of the mystery man for whom Mr Renehan organised a cremation in 2003.

Mr Delaney was homeless when he went missing from a hostel in Ancoats, Manchester, in April 2000. His family reported him missing and police issued an appeal and photograph.

Traumatic ordeal: Mr Renehan spotted his father John Delaney on TV, five years after he thought he had cremated him

After a badly decomposed body was found in the grounds of Manchester Royal Infirmary in January 2003 wearing similar clothes and with similar old wounds, police said it was Mr Delaney without carrying out DNA tests.

Mr Renehan declined the opportunity to view the body because of its condition. There were no suspicious circumstances and a coroner recorded an open verdict.

But now it has been established that Mr Delaney was found wandering dazed in Oldham in May 2000 and was taken to hospital with amnesia resulting from a brain injury.

He was unable to hold a conversation or tell anyone his name. It is believed he had received a blow to the head ten days earlier.

He spent the next eight years in the care home, where he was given the name David Harrison. It was in April this year that he featured on a daytime TV programme.

Missing posters: Police and social services renamed John Delaney 'David Harrison' and released images of him in an effort to find out his true identity

By coincidence, engineer Mr Renehan was doing night shifts for the first time in his life and happened to tune in at exactly the right moment.

Yesterday, the father of two from Didsbury, South Manchester, said: 'I was getting ready to go to sleep when I turned on the TV. I don't watch a lot of daytime television and it was probably the first time I'd done it.'

Since their emotional reunion a fortnight ago, Mr Renehan has spent time with his father every day at the care home, looking at old family pictures together as Mr Delaney tries to piece together his past.

Mr Renehan is also thinking of the family of the man he had cremated. 'I feel sorry for them and I don't know how anyone is going to find out who it was,' he said.

In 2003, DNA tests were not widely used to identify decomposed bodies. But a spokesman for Greater Manchester Police said the force accepted that inquiries to establish Mr Delaney's identity when he was admitted to hospital were 'not sufficient' and apologised to Mr Delaney's family for their 'traumatic ordeal'.