ONE of Britain's most notorious killers - 'Black Panther' Donald Neilson - who killed an East Lancashire sub postmaster, has died in hospital.

Neilson was given four life sentences in 1975 and was one of a small group of notorious prisoners who were told they would spend the rest of their lives behind bars.

The 75-year-old murdered heiress Lesley Whittle in 1975 and also shot dead three sub-postmasters - including Derek Astin the sub-postmaster of Baxenden Post Office - during armed robberies.

Neilson became Britain's most wanted man before he was finally brought to justice in 1976 at Oxford Crown Court.

It was revealed as long ago as 2009 that he has the latter stages of motor neurone disease.

Prison Service spokesman said: "HMP Norwich prisoner Donald Neilson was taken to outside hospital in the early hours of Saturday, December 17, with breathing difficulties.

"He was pronounced dead there at approximately 6.45pm on Sunday, December 18.

"As with all deaths in custody, the independent Prisons and Probation Ombudsman will conduct an investigation."

Yesterday Mr Astin’s daughter, Susan, who still lives in Baxenden, said she did not want to talk about Neilson.

Mr Astin was killed in 1974 when at 4am on September 6, Neilson, who was masked, entered the post office house in Baxenden where he and his family were asleep upstairs.

Mr Astin was confronted by Neilson and was shot in the shoulder and then in the back.

Although dying from his wounds Mr Astin managed to push the raider downstairs.

Sixty police officers took part in the investigation, led by Det Supt Mounsey, head of Lancashire CID.

Neilson was later wanted for one of the most chilling murders in the annals of British crime.

Seventeen-year-old heiress Lesley Whittle was found hanging naked from a wire noose in a Staffordshire drain after she had been kidnapped.

High Court Judge, Mr Justice Tear, said Neilson, who was 39 when convicted, “never set out without a loaded shotgun or other loaded weapon and he never hesitated to shoot to kill whenever he thought he was in danger of arrest or of detection”.