Summer Grant's father ran after a bouncy castle as it was blown 300 metres down a hill with the seven-year-old inside before her death, a court has heard.

The Hellesdon schoolgirl had been enjoying a family day out at Harlow Town Park in Essex when the inflatable was blown away, Chelmsford Crown Court was told.

Fairground worker William Thurston, 29, and his wife, Shelby Thurston, 26, both deny manslaughter by gross negligence and a health and safety offence.

Tracy Ayling QC, prosecuting, said Summer was with her father, Lee Grant, and other family members at Thurstons Fun Fair on Easter Saturday in 2016, and that Storm Katie was expected to arrive by Easter Monday.

'The weather was cold and windy,' said Ms Ayling. 'Summer was playing in a bouncy castle that was one of the fair's attractions run by these two defendants.

'While Summer was in the bouncy castle, it blew away from its moorings, bounced 300 metres down a hill; having hit a tree, it came to rest.'

She said Summer, who was a pupil at Valley Primary School in Hellesdon, was rescued from inside the bouncy castle and taken to hospital but died from her injuries.

The two defendants, of Whitecross Road, Wilburton, near Ely, Cambridgeshire, sat side by side in the dock as Ms Ayling opened the prosecution case on Tuesday.

'It's the Crown's case that they breached the duty of care they owed to Summer Grant by failing to ensure that the bouncy castle, called a circus super dome inflatable, was adequately anchored to the ground and failed to monitor weather conditions to ensure it was safe to use,' she said.

Ms Ayling said Summer's father had heard a scream.

'He turned and saw that the dome inflatable had lifted into the air, appeared to hit a caravan before flipping over,' she said. 'He said 'My daughter's in there'.'

Mr Grant ran after it but it was moving too fast for him to catch it, Ms Ayling said.

Witnesses described seeing the bouncy castle 'cartwheeling in the air, cartwheeling down a hill and only stopping when it hit a fence'.

Ms Ayling said William Thurston was among those who chased the bouncy castle as it blew away and, when he went to help Summer, it appeared 'she was very badly injured and struggling to breathe'.

Father tells of efforts to save Summer

Giving evidence in court on Tuesday, Mr Grant said he was at the fair with his two daughters Summer and Lily, who was five years old at the time.

He said they first went on the waltzer ride, then disaster struck when Summer went on a bouncy castle.

'I just heard my mum scream 'no' and within seconds it blew away,' said Mr Grant. 'I just saw some sort of cable flying in the air and it just blew away.

'I remember it blowing over some sort of caravan and kept on going over the field.

'I started running after the bouncy castle down the field.'

He continued: 'It was 30 to 50ft in the air and just rolling down the field, just rolling and rolling.

'I think it hit a tree. At the end of the field, it came to a halt when it hit the fence.

'I couldn't find her. I couldn't find the entrance to the bouncy castle as it had deflated by the time it reached the end.'

He said he saw someone go into the bouncy castle to bring Summer out.

Mr Grant said he arrived at the fair with his two daughters and his mother Sharon Stephens and sister Tasha Stephens between 4pm and 5pm on March 26, 2016.

He said he first went on the waltzer ride with his daughters, then they went to two bouncy castles that were side-by-side, a dome and a slide.

'The bloke who was running both told me it was £3 for both for five or 10 minutes,' he said, adding that the man was black and of slim build.

He said Summer and Lily both went on the dome first, then the slide, then Summer went back on the dome alone 'as she preferred that one'.

Asked about the weather at the time, he said: 'It was spitting lightly, a little bit windy, nothing to suggest a bouncy castle was about to blow away.'

He said he had seen another large bouncy castle being deflated as they arrived at the fair, but thought this was due to the time of day.

His daughters were visiting him in Harlow, where he lives, from Norwich where they lived, he said.

Tracy Ayling QC, prosecuting, said a yellow weather warning was in place on March 24 2016 and was still in place on the day of the incident two days later.

A meteorologist said the highest gusts during the afternoon had reached 35 to 40mph, Ms Ayling said.

The trial continues.