A murderer has escaped from prison, British police say.
John Massey, 64, made off from Pentonville Prison in Islington, North London at around 6.30pm (0400 AEST), police said.
Scotland Yard said he is considered "potentially dangerous" and should not be approached.
Massey was sentenced to life imprisonment for the murder of a man at a pub in Hackney, East London in 1975.
A police spokesman said: "Police are appealing for help in tracing a convicted murderer who has escaped from HMP Pentonville.
"He is considered potentially dangerous and should not be approached by the public if he is seen."