One of Britain's most prolific serial killers has been seen out on day release from prison.

Patrick Mackay, 70, who grew up around Dartford and Gravesend, was jailed in 1975 after confessing to brutally murdering 11 people.

This week he has been spotted walking around a city centre bus station.

He was seen in Bristol wearing glasses and a baseball cap while out on day release from open prison HMP Leyhill in Gloucestershire, the Daily Mail reported.

Mackay was jailed for life with a minimum of 20 years in 1975 for three killings but originally owned up to eight more before retracting his admission.

He was 23-years-old when he was jailed for stabbing and strangling pensioner Isabella Griffiths, 87, in Belgravia, central London, in 1974 and 89-year-old Adele Price the following year.

Mackay returned to Kent near to his old stomping ground and befriended a priest.

Father Anthony Crean was later hacked to death with an axe and left in his blood-filled bath in the village of Shorne, near Gravesend.

The other eight attacks, which Mackay initially admitted, remain unsolved and a judge has said they will stay on file.

Dubbed "Britain’s forgotten serial killer", the 70-year-old, who now goes by David Groves, is the country's longest-serving prisoner.

Mackay was expected to go before a parole board in April after applying for early release. He had been set for a hearing last September but, like his previous bids, it was rejected.

Although he became eligible for release at the end of his minimum term in March 1995, Mackay has always been deemed too high risk to be safely managed in the community.

After being spotted this week on day release, Dartford MP Gareth Johnson, who has previously spoke of his reservations at the killer’s release in the Commons, told The Sun that he was “still young enough to kill again”.

The killer spent the first 27 years of his sentence in a top security Category A jail before being moved to open prison HMP Leyhill in Gloucestershire.

An Amazon Prime Video documentary was released earlier this year featuring accounts from former Kent Police officers, forensic psychologists, and criminologists.

Neighbours have also shared their recollections of the Mackay family when they moved to Frobisher Way in Gravesend.