A missing Norfolk man discovered in a London hospital was taken there by British Transport Police officers who were oblivious to a massive four-day search going on to find him.

Police forces will discuss whether there are any 'lessons to learn' in the case of John Boyd, who suffers from dementia.

Mr Boyd, 77, had last been seen on Wales Court in Downham Market on the afternoon of Tuesday, January 4, before making his way to London.

A large-scale search operation was launched to locate him, which involved drones and foot patrols, and Norfolk police carried out enquiries with its partners to review any CCTV available and to check with local hospitals.

This included CCTV at Downham Market train station, controlled by British Transport Police (BTP).

But the pensioner was not seen on any footage at the station or boarding any trains.

Police officers were also assisted by volunteers from Norfolk Lowland Search and Rescue, who were seen checking hedgerows and fields alongside the A10 on the east of Downham on Saturday.

His disappearance was also circulated on national police systems.

Efforts to find him continued on Saturday, the day Norfolk police and his family were told that he had been found at King's Cross Station in London on the same day he went missing.

It was a TV appeal by Chief Inspector Rob Button which prompted his discovery.

Chief Superintendent David Buckley, Norfolk’s County Policing Commander, said: "Our ongoing work and subsequent television appeal, revealed that John had, in fact, travelled to King's Cross train station, where he was found by officers from the local force and taken to hospital where he remained safe, being cared for by hospital staff.

"Due to John’s vulnerabilities, no-one in London knew who he was until seeing the television appeal.

"This resulted in Norfolk Police being contacted and our enquiries moved to London where we were able to confirm it was John."

A spokesperson for BTP said: “Officers were called to King's Cross station shortly before 5pm on January 4 following concern for the welfare of a man.

"Paramedics also attended and the man was taken to hospital for assessment.”

Mr Buckley said that the force works with the information it has at the time and that evidence suggested the 77-year-old would be in the Downham Market area.

He added: "While anyone reported missing can travel, if determined, great distances, policing experience tells us that the vast majority of people remain local and our searches will always be informed by proximity of where the person went missing, lifestyle consideration such as habits and evidence such as sightings.

“Clearly, the most important thing is that John is safe and well.

"As a matter of course, we will be speaking with partner agencies in London to see if there are any lessons to learn to make sure there were no missed opportunities which could have led to John being identified as found sooner."

The Chief Superintendent expressed how pleased Norfolk police were that Mr Boyd has been reunited with his family and thanked local communities and volunteers for their support in the search.

Mr Boyd's family also paid tribute to people in Downham Market, after people rallied round to help.