The retired engineer and ex-Marine is a keen sportsman and charity fund-raiser, who has combined his hobbies to collect more than £1,000 for charity for a 17th year in a row.

Mr Williams, of Groby Road, Leicester, raised £1,220 when he swam 25 miles in the Red Sea, in Egypt, and a 25-mile cycle around Rutland Water.

He completed the sponsored challenge in May and is now ready to present the cash to the Leicester branch of the Alzheimer's Society.

The charity is close to Mr Williams's heart because his wife, Audrey, for whom he is a full-time carer, has the illness.

Mr Williams, a volunteer lifeguard tutor, who grew up in Belgrave, in Leicester, has raised around £18,000 for Leicester charities - including Rainbows children's hospice, in Loughborough, and many homes for the elderly - over the past 17 years.

He said: "I do it because I enjoy it. I have a soft spot for charities and I just like getting out there and doing challenges."

Mrs Williams, 82, was diagnosed with Alzheimer's six years ago after she fell down some stairs, suffering a fractured skull.

Mr Williams, a first-aid tutor, saved his wife's life by resuscitating her before emergency services arrived.

He said that as his wife was suffering, the Alzheimer's Society was a good charity to choose to benefit from his challenge this time round.

Mr Williams said: "Some days you wouldn't even realise that anything was wrong with her, but other days it's different.

"People don't understand what a horrible thing Alzheimer's is."

Mr Williams, who was recently named Leicestershire's oldest lifeguard, received much of his sponsorship from fellow members of the Leicestershire and Rutland Masonic Society and South Leicester Rugby Football Club.

He said he would continue to raise money for the Alzheimer's Society.

Diane Smith, manager of the charity's Leicester branch, said: "That Harold has managed to do this on top of caring from his home is an exceptional achievement.

"Harold is an absolute star and one of many people in Leicester who are caring for dementia and Alzheimer's sufferers. They are unsung heroes."