For he was the on-call orthopaedic registrar at the town's Queen Elizabeth Hospital that morning and had given up hope of competing after his cover arrangements fell through the previous evening.

Just 40 minutes before the start, Mr Hennessy (30) was preparing to carry out an operation to mend a child's fractured elbow when the consultant, James Jeffrey, asked him if he was not supposed to be taking part in "this race around the houses".

Mr Hennessy said: "I said, 'Yes, I have entered it but my cover arrangements haven't happened and I can't do it'. He phoned another of my colleagues, Shantanu Mandel, and asked if he could come in and take the bleep 'because Andrew has to go and win a race in town'.

"Then he said, 'Go into town, win that race and come back, will you?' – and I felt obliged to do just that because those were his strict instructions!"

Mr Hennessy, who had running gear on under his work clothes, parked half-a-mile from Tuesday Market Place and jogged to the start, getting there with about 15 minutes to spare.

He recalled: "I saw a few of my competitors looking very serious and warming-up, but mentally I felt relaxed because I had dismissed any thoughts of running as I didn't think I would be able to.

"It turned out fantastically. It was a good race and a fast course and I set out with the intent of running as hard as I could for as long as I could, and if I was still in with a chance at the end that would be a bonus."

"Up to the last half-kilometre there was myself and Darren Fowlie and I thought if I didn't win I would be in trouble with my boss, so I just went for it," he said.

"After winning, I ran back to my car and returned to the hospital. I had to miss the prizegiving because I was hoping I might still be able to join in the operation – but they had just finished and were walking out of the theatre."

Mr Hennessy has been running for about 20 years and is a life member of Wells City Harriers, although he currently lives and works in Lynn.