Fellow Aerosmith fan and personal trainer/fitness instructor Rob Harriss (26) has cajoled and supported her into doing things she never dreamed she could to get her weight down from 15st 2lbs to eight stone four.

She said this week: "I was a fat mummy – the one left holding the coats and lunchboxes when the rest of the family had fun on the rides at Alton Towers.

"Just over two years ago, my daughters were growing up and I had more time, so I made a decision to eat more healthily.

"Then I went to Everybody's Gym in Spalding. I hadn't seen a gym teacher since school and I did everything possible to avoid them then.

"But the gym welcomed me so I signed up and a few weeks later Rob and I recognised each other as fans – we conspired to get our song played when we could: Love in an Elevator.

"He found my inner athlete. So many things I said I couldn't do – even running on a treadmill – he knew I could and that made me go for it.

"Now he writes my programme every six weeks.

"I am a regular adrenalin junkie now and at 48 I am fitter than I have ever been in my life!"

The pair have more in common than their song: Sarah is a tiny five foot and muscle-man Rob a stocky five foot three.

His tough love approach comes from having to be tough with himself.

He said: "I wasn't allowed to play sport at school because of a knee problem and at 17 I was 13 stone.

"Working out was a case of having to, now it's a way of life."