The court found that Morrisons as an employer was not "vicariously liable" for a data breach, a victory for the grocery firm which had faced compensation claims from over 9,000 former and current employees over the incident.

The case was Britain's first data leak class action.

In 2017, London's High Court found Morrisons was liable for the 2014 theft and publication of the data by finance worker Andrew Skelton, who was later jailed for his offences.

But that ruling, which had also been backed by the Court of Appeal, was overturned on Wednesday by Britain's Supreme Court.

In a written judgement, one of the Supreme Court judges Robert Reed said Skelton's wrongful conduct "was not so closely connected with acts which he was authorised to do" for Morrisons to be judged liable for his actions.

"The circumstances in which Skelton committed wrongs against the claimants were not such as to result in the imposition of vicarious liability upon his employer," he wrote.

"Morrisons cannot therefore be held liable for Skelton?s conduct."

(Reporting by Alistair Smout; editing by Michael Holden)