Williams was 18 when Marian Bates was killed

Peter Williams was appealing against the sentence handed to him at Stafford Crown Court in March.

The 20-year-old, of no fixed address, had helped a gunman to escape after the bungled raid in Arnold, Notts, in 2003.

Mrs Bates, 64, was shot dead as she leapt between the armed robber and her daughter Xanthe.

'Not excessive'

Williams, who was just 18 at the time of the killing, was present in the dock at the Court of Appeal in London when Lord Justice Rose, sitting with Mr Justice Crane and Mr Justice Openshaw, rejected his appeal.

Lord Justice Rose said that although the term was severe, it could not be characterised as manifestly excessive.

The gunman, who police believe to be serial offender James Brodie, has never been caught.

The three judges also rejected an appeal against the sentence of Craig Moran, who was jailed for 13 years for plotting to rob Mrs Bates.

Moran, 23, and another man, Dean Betton, 24, were found guilty of conspiring to rob Mrs Bates's shop.

Betton, from Broxtowe, Nottingham, and Moran, of Bestwood, Nottingham, kept watch on the shop in Front Street 24 hours before the murder and were in the getaway car used in the offence.