William and Shelby Thurston were convicted of the gross negligence manslaughter of seven-year-old Summer Grant “I was told that adequate wind meters can be purchased for £100 or less. I would urge the Health and Safety Executive to take the steps necessary to make their use compulsory at fairgrounds to prevent another tragedy like that of Summer Grant.” Summer Grant Fairground bouncy castle operators should be forced to measure wind speed, a judge has said after a couple were jailed over the death of a young girl.Summer Grant, seven, was killed after a gust of wind lifted an inflatable from its moorings and sent it “cartwheeling” 300 metres (980ft) down a hill at an Easter fair in Harlow, Essex.William Thurston, 29, and 26-year-old Shelby Thurston were on Friday each jailed for three years after they were both found guilty of manslaughter by gross negligence.Jurors at Chelmsford Crown Court had found they were responsible for the “entirely preventable” death of Summer, who died after being blown away in a bouncy castle they did not properly secure.Mr Justice Garnham called on the Health and Safety Executive to take the steps necessary to make it compulsory for fairground operators to have proper wind speed measuring equipment.He added: “On hearing the evidence in this case, it strikes me as extraordinary in the 21st century that it should be commonplace in the fairground industry, as the evidence I have heard suggests it is, that inflatable play equipment should be operated and open to the public without the operators using proper wind speed measuring devices. The couple, of Wilburton, near Ely, Cambridgeshire, were also found guilty of a health and safety offence following the incident on March 26 2016. They were sentenced to a further 12 months’ imprisonment for that offence, to run concurrently.Sentencing them, Mr Justice Garnham said the couple “took the most monumental risk with children’s lives by continuing to allow children on the bouncy castle” after they decided to close the big slide, “and that risk-taking cost Summer her life”.Reading a victim impact statement, Summer’s mother Cara Blackie described how she screamed when she heard the news of her daughter’s death.Unable to continue giving the emotional statement, Ms Blackie sat down as prosecutor Tracy Ayling QC continued reading.She said: “I never thought that my Summer playing and having fun on the bouncy castle would end her young life.”Video: Emergency services race to fairground Summer Grant died in hospital after she was rescued from the inflatable Credit:Essex Police/PA He said: “When Summer died, I felt as if I died too. I felt as if I had nothing left to live for because she was my beautiful angel.”Mr Grant said he had a number of questions, including why the bouncy castle was not tied down properly, if the weather was to blame then why was it put up, and why was one person looking after two bouncy castles.Prosecutors said the defendants failed to ensure that the bouncy castle was “adequately anchored” to the ground and failed to monitor weather conditions to ensure it was safe to use. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily  Front Page newsletter and new  audio briefings. William and Shelby Thurston were convicted of the gross negligence manslaughter of Summer GrantCredit:Joe Giddens/PA A yellow Met Office weather warning was in place on the day of the incident, two days before Storm Katie was due to arrive.Summer was rescued from within the bouncy castle and taken to hospital where she died from her injuries.Speaking after the sentencing, Nicola Jaynes, from the Health and Safety Executive, said the death was “entirely preventable”. In a statement read to the court Summer’s father Lee Grant said the youngster’s death has had an ongoing impact on his life. read more