The mother of an epileptic teenager who died after suffering a seizure in a school pool, says she should have had one-to-one supervision in the water.

Accomplished swimmer Hayley Williams, 13, had been enjoying playing in the pool at Ashgrove Special School for autistic children in Penarth, when she dived under the surface and suffered a seizure, Cardiff Coroner's Court heard.

Despite desperate attempts to save her, she later died at Cardiff's University Hospital of Wales.

Her normal support assistant Kerry Osborne, who is afraid of water, had been supervising Hayley from the poolside. A support assistant and teacher were in the water with Hayley and three other boys, the court heard.

Recording a verdict of accidental death, coroner Mary Hassell said there was no evidence to suggest that if Hayley had a one-to-one supervisor in the water, it would have saved her.

But speaking after the inquest, Hayley's mum Gaynor said: 'Swimming was Hayley's life, but if I'd have been aware there was nobody with her one-to-one, I may have thought twice about letting her in the pool.

'This one-to-one issue has terrible implications for any parent of a child in a pool with epilepsy. Lessons have to be learned and other parents have to know that one-to-one can be interpreted in different ways.

'I was under the stupid assumption that someone was in the pool next to my child.

'We knew Kerry Osborne didn't go in the water, but we thought someone else did.

'We don't know if it would have saved her, but someone on the poolside isn't enough. Hayley could have seizures so quickly.

'Hayley was a member of Newport Seals swimming group at Newport Leisure Centre and they were always one-to-one with her.'

Support assistant Kerry Osborne told the court she was watching Hayley bobbing in the water.

She looked at another boy in the pool, then saw support assistant Charlene Lyle holding Hayley in the water as she was having a seizure.

She said: 'It was as quick as that.'

Support assistant Charlene Lyle said she was next to Hayley in the pool when Hayley dived under and did not re-surface.

She said: 'She went under the water. I was listening to another boy, then she wasn't there.

'I thought, 'where's Hayley?' I saw her shape under the water and grabbed her by her bathers and pulled her out of the water. It was a split second. She was fitting.

'We got her to the poolside and gave her CPR.'

Head Brian Bayford said staff were fully aware of Hayley's epilepsy.

He said she loved to swim and with a lifeguard and Ms Osborne on the poolside, and two people in the pool, with only four children in the water, he was satisfied she was supervised.

Pathologist Derek James said Hayley had died after having an epileptic fit while swimming and water blocked her airways.

Mary Hassell said: 'Hayley died doing something that made her very happy.

'Although the one-to-one person was poolside, the person who was in the pool was very very close to her. She was never more than a couple of arm's lengths away.

'Everyone tried their very best to give Hayley CPR.'

She said Hayley fell into the small category of people who have a seizure, are in the water for a very short time and are 'irretrievable'.