The 11-year-old primary school pupil who died during a swimming lesson at Thame Leisure Centre got into difficulty as he swam under water, his headteacher said.

Nathan Matthews, a pupil at Stokenchurch Primary School, died suddenly in 2ft 6in of water during a swimming lesson on Monday.

A post mortem was due to be held today and the inquest into his death opened and adjourned before the end of the week.

The Health and Safety Executive also plans an investigation with South Oxfordshire District Council.

Nathan's parents, Terry and Penny Matthews, said their son had been bullied at school and feared he may have been held under water during the lesson, which was attended by 88 pupils.

But Thames Valley Police say they have ruled out foul play and are not treating his death as suspicious.

Nathan was dragged from the water by a lifeguard, but poolside resuscitation attempts failed.

He was taken to Oxford's John Radcliffe Hospital, where he was pronounced dead.

School headteacher Andrew White said: "I fully understand Nathan's parents are desperately searching for answers as to why this happened.

"There was no sign of physical contact with any other pupil while Nathan was in the swimming pool.

"Nathan appears to have got into difficulties when he went down for a relay ring.

"A fellow pupil very quickly noticed he did not surface and a member of school staff pulled Nathan out."

Nathan was one of five children in the water at the time and had been swimming the width, rather than the length, of the pool.

The children were supervised by a leisure centre lifeguard, two instructors and three school staff.

Thames Valley Police spokesman Tim Wiseman said: "Nathan's death is not being treated as suspicious.

"Investigations are carried out as a matter of course after all sudden deaths and we await the results of the post mortem."

The National Curriculum dictates that all schoolchildren must be able to swim 25 metres at the age of 11 and take tests in speed, distance and survival.

Nathan, one of six siblings, was part of a school group that had been using the leisure centre, which was opened last year by the Earl and Countess of Wessex.

The school's own swimming pool was being refurbished.

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