An inquest has opened into the deaths of a seven-year-old girl and a teenager who drowned in a holiday village swimming pool last May.

Police officers, some of them members of the police tactical support unit in body armour, have been drafted in for the duration of the case, due to its emotive nature. The inquest is being held at the Shire House in Bodmin, and is likely to finish today (Friday) following its opening on Wednesday.

Vanessa Gregson, l9, and Tshan Kamara, drowned on Thursday May 20 while staying at Honicombe Manor Holiday Village near Callington with family and friends. They were both from Liverpool. The inquest heard Vanessa, a nursery assistant, had been in charge of five youngsters aged four to nine, all children of Darren Kamara, who had returned to Liverpool but was due to collect them on the Friday. One witness on holiday at the same time described the family as a happy one with the children appearing well-behaved and friendly.

There were no lifeguards on duty at the pool at the time, around 4.30pm, and site manager Carolyn Sanders said this was because it was not peak season. Mrs Sanders, painter Gordon Knott and maintenance man Robert Webber had jumped into the pool and pulled the girls out, after the alarm was raised by some distressed children, but were unable to revive them. Both were flown to Derriford Hospital, Plymouth. Tshan suffered extensive brain damage, and a life support machine was switched off two days later.

A police diver, Pc Anthony Shergold, who investigated the pool after the incident, said a sudden steep drop into the deep end, had made him lose his footing.

The inquest, carried out by East Cornwall coroner Dr David Bruce, was told by pathologist Dr Guyan Fernando that Miss Gregson had had a large bruise on the top of her head. He said it was possible she had struck part of her head on the bottom or the side of the pool which made her unable to help herself. There was evidence of slight amounts of cannabis in her body, but it was said that this did not imply the recent taking of cannabis, or that her judgement was impaired.

There was no evidence of alcohol. Vanessa was said to have been a strong swimmer and life-saver.