Prince William surprised children at a Stevenage school after he dropped in for a spot of lunch in the school's canteen. The Prince, who is an East Anglian Air Ambulance pilot, flew in to the playing field at John Henry Newman School, after transporting doctors from nearby Lister Hospital.

The Prince took his lunchbreak in the school canteen after the flying mission, much to the excitement of the school children. Head teacher Clive Matthew said the royal visit was "completely unexpected". "It was really quite bizarre. We have the air ambulance use the school site quite regularly and whenever they land the staff go out, we clear the field of children and offer the crew refreshments," he explained.

"We didn't realise who was on the helicopter at the time. And then Prince William jumped off and came into the school."

The Duke of Cambridge was not afforded any special treatment during his impromptu visit and happily queued along with the children for his lunch and sat and chatted with them while he ate. "He was great. He queued up with the children, he got himself some lunch and sat down," explained Matthew. "Then he was surrounded by a group of Year 11 boys who had a chat with him ... they asked him if he had enjoyed the Christmas holidays and he told the students he'd had a lovely time.

"He was really nice and it was lovely the visit was so spontaneous. I think it made the students' year," said Matthew. The headteacher revealed the royal tucked into a lunch of roast chicken, cauliflower cheese and vegetables, but skipped dessert. The prince donated the cost of the meal to the school's children's charity. "[William] did compliment the meal, saying it was very good," he added.

The students also made the most of the opportunity to take photos and tweet messages about the Prince's visit on social media. Posting a picture Niamh Crawley wrote: "When you walk into your dining room to find Prince William having a spot of lunch! #what"

The Duke of Cambridge returned to his duties for the local air ambulance service after the Christmas holiday. He recently moved to a new purpose-built base in Cambridge International Airport as part of his work with the East Anglian Air Ambulance.

The 33-year-old royal, who was earlier seen dressed in a high-visibility jacket, is believed to have flown on several missions in the course of the day as well as carrying out maintenance work during the nine and a half hour shift.

William has been working for the air ambulance service since last summer after leaving the RAF, where he flew search and rescue helicopters for several years. He flies an EC145 T2 aircraft and responds to emergencies in Norfolk, Suffolk, Cambridgeshire and Bedfordshire, ranging from road accidents to heart attacks.

The charity regularly completes more than 150 missions each month. The royal, who is second in line to the throne, donates his salary to charity.