The Supreme Court has ruled that a woman who nearly drowned in a school swimming lesson run by an outsourcing company can pursue a compensation claim against the local authority.

Essex county council had hired contractors to take the swimming lessons in 2000 at Whitmore Junior School in Basildon, but Annie Woodland, then aged 10, suffered severe brain damage after getting into difficulty in the water.

The swimming teacher and lifeguard who, it is claimed, negligently failed to notice that the girl had got into difficulties were not employed by the county council.

A £3m claim for damages was rejected in 2011 and the decision last year upheld by the Court of Appeal, which said it would not be fair, just or reasonable to impose a non-delegable duty upon the local authority.

In a Supreme Court judgment given today, Lord Sumption said the case met key criteria to suggest there was a reasonable burden on the council through its non-delegable duties of care.

He said the underlying principle behind these duties included where the claimant is a patient, child or vulnerable person and where the claimant is in the actual charge, custody or care of the defendant.

Sumption added: ‘The alleged negligence occurred in the course of the very functions which the school assumed an obligation to perform and delegated to its contractors. It must follow that if the latter were negligent in performing those functions and the child was injured as a result, the educational authority is in breach of duty.’

The appeal will be regarded as a landmark case at a time when schools and hospitals are increasingly contracting out work to third-party providers.

Catherine Leech (pictured), partner at Manchester firm Pannone, who was solicitor for the claimant, said the judgment gives a ‘blanket of reassurance’ for parents and should lead schools to review procedures about outsourcing.

‘It does not put an unreasonable burden on schools, headteachers or governors,’ said Leech. ‘If they have robust selection of independent contractors, a contract between them and the school and, crucially, check they are properly insured, the school can protect itself.’

The case will go back to the high court in Manchester next year for a hearing on liability and quantum.