Friends visited the park yesterday to lay flowers at the scene where Robbie was pulled from the water.They told how the teenager got into difficulty while trying to swim to an island in the middle of the North Metropolitan Lake at the Lee Valley Park.Ryan Soltwell, 18, said: “I woke up and saw it all over social media and I asked a friend what happened.”She said he had come river-jumping and swimming and he drowned. One of Prince William’s final assignments as an air ambulance pilot has ended in tragedy, after he could not save a drowning 17-year-old boy. The teenager, named by friends as Robbie Lea, got into trouble in a lake at the Lee Valley Park in Cheshunt, Hertfordshire on the hottest day of the year. The Duke of Cambridge was scrambled to pilot an Air Ambulance helicopter to the country park after the emergency services were alerted.The Duke of Cambridge was scrambled to pilot an Air Ambulance helicopter to the country park after the emergency services were alerted.After an hour long search the body of a boy was pulled from the water. Tragically he was pronounced dead at the scene, the first person this year to drown while out swimming in the recent spell of hot weather. “We’ve all done it before but nothing’s ever come out like this.”Morgan Harrison, 17, who also went to the scene, said: “He was just going out and having fun. I think it’s just really horrible.”Stuff like this happens, he wasn’t doing anything stupid I think he was just having a good time, it was a hot day and he obviously wanted to cool down he has not realised the danger.”I first heard last night.”I was in bed and I about to go to sleep and I got a text message saying people keep saying Robbie’s missing and he’s passed away and I couldn’t believe it and it was all over social media.”I was just really sad, distraught to be honest.”I didn’t really get to sleep I was just worrying about his family, my boyfriend and his friends, the people he was with.”I’ve just seen lots and lots of people posting pictures saying I can’t believe you’re gone.”I would like to say he’s got a lot of people missing him, he’s got a lot of support and that we all love him.”Robbie, who attended Goffs School in Cheshunt, had recently started studying engineering at Hertford Regional College. Think carefully before swimming in unsupervised areas and look out for signs and advice about the specific dangers at the location where you are swimming.Chief Fire Officer Darryl Keen An eye witness, who wished to remain anonymous, said: “We knew something was up when a helicopter was flying extremely low just over the Lee Valley Park.”We could see it was landing so ran over to see what was going on.”Little did we expect to see Prince William himself flying the helicopter.”It was a very surreal moment when he left the helicopter to help with the search and rescue, for he had no visible guards or protection.”He arrived in an East Anglia Air Ambulance with one other co-pilot.”The man said he did not see a body being retrieved from the river, but that a group of people nearby had to be ushered away from the scene. Hertfordshire Fire and Rescue confirmed that Robbie was found following an extensive bankside and water search.Chief Fire Officer Darryl Keen said: “We were called yesterday evening to reports of a boy who had got into difficulties while swimming at Lea Valley Park in Cheshunt.”Following a search we recovered the boy from the water. Sadly, he was pronounced dead at the scene and our thoughts are with his family and friends at this time.”Now that the weather is so warm it’s very tempting to cool off with a swim. Eyewitness Dave Samuels said: “There were two helicopters, one police and one air ambulance, there were emergency services everywhere including water rescue with people getting boats ready.”Whatever had actually happened, you couldn’t say the emergency services hadn’t tried, I have never seen so many.”A Hertfordshire Constabulary spokeswoman said: “A search led by the fire service was carried out.”The boy was recovered from the water but sadly he was pronounced dead at the scene.”There are no suspicious circumstances surrounding the incident and a file will be prepared for the coroner of Hertfordshire.”Lee Valley Regional Park is a 10,000-acre 26 miles long linear park which runs through the northeast of Greater London, Essex and Hertfordshire.The area includes a network of rivers, canals and lakes. Swimming and paddling is not permitted in the park. He wasn’t doing anything stupid I think he was just having a good time, it was a hot day and he obviously wanted to cool down he has not realised the danger.Morgan Harrison Videos taken at the scene show the Duke of Cambridge landing his helicopter, and then walking towards the scene at around 8.00pm on Thursday. Prince William at the lake at Lee Valley ParkCredit:Herts Mercury / SWNS.com Prince William in the air ambulance at the lake at Lee Valley ParkCredit:Herts Mercury / SWNS.com 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. “However, even the strongest swimmer can get into difficulties and we would advise people to think carefully before swimming in unsupervised areas and look out for signs and advice about the specific dangers at the location where you are swimming.”The Duke of Cambridge, who is a pilot for the East Anglian Air Ambulance, landed the helicopter on the river bank at approximately 7.45pm.Paramedics and a water rescue team from the Hertfordshire Fire and Rescue Service also attended the scene.