Racing hero Lewis Hamilton made a secret pit-stop at his old school in Stevenage this morning, delighting pupils who had no idea he was coming.

Clearly delighted to be back where he said he had spent his happiest school years, the youngest ever Formula 1 world champ walked into a packed assembly at Peartree Junior School to gasps from the children.

The 25-year-old then spent half an hour answering their questions on everything from what it’s like to be famous: “It’s very, very strange. I go to Tesco and everyone recognises me”, to what it is like driving an F1 car: “I tried to imagine what it was like, but my imagination was nowhere near – your brain gets sucked back in your skull”.

After hugging one of his former teachers, Elaine Holman, his “favourite teacher” at Peartree, Lewis presented the school with a signed T-shirt of the kind he and his McLaren teammates wear if they have won a grand prix.

Mrs Holman, who Lewis knew as Miss McKeown, said he had been a good, hard-working pupil and only rarely naughty.

The appearance of the race ace was kept top secret. The majority of teachers only found out this morning and the pupils had no idea he was coming.

But deputy headteacher Ellie Shaw said: “We did tell staff they might want to do their hair and their clothes.”

On what it is like to have such a successful former pupil Miss Shaw said: “When he won the world championship it was lovely to talk to the children about what they can achieve. Times are hard and things are tough in this neighbourhood at the moment. It is something to aspire to - your dreams can come true.”