It was like any other late summer’s day when retired hill farmer Tom Robb headed out for a walk in the Stirlingshire countryside where he had farmed for over 50 years.

But that was four years ago and Tom, who suffered from dementia, hasn’t been seen since.

Despite extensive searches by family, friends, mountain rescue teams, a helicopter, specialist police dog teams, no trace of him has been found.

Now he is to be remembered later this month with a special seven mile trail race through the Forestry Commission woodland where he was last seen.

The Tom Robb Memorial Trail Race has been organised by his family for Saturday August 27 within the Carron Valley Forestry to raise funds for Alzheimer's Scotland and Ochils Mountain Rescue “to support the amazing work they do.”

Tom’s daughter Moira Paterson, 44, said the mountain rescue team had been prominent in the search for father.

She said her father had been almost 75 when he went missing and had developed dementia in his late 60s. He had been a fit man for his age and where he was walking was close to the farm he had worked for half a century.. But his sense of direction had waned.

The last confirmed sighting of Mr Robb was at about 4.30pm on August 25 2012 at Duncarron Fort in the Carron Valley where a music festival was being held. He had also been seen a short time earlier by a group of walkers in the Meikle Bin area.

Mrs Paterson said “We searched for months after the official search was stood down, but we found nothing, not a trace.

“There is a reservoir in that area and the theory that made most sense was that he went into the water. He couldn’t swim. But they had searched round it using dogs specially trained to look for people who may have gone into water. Apparently they would have picked up any trace of him round the banks.”

She said “It just doesn’t make sense to me.”

The mother of a teenage son (17) and daughter (15) explained the idea of the run.

“I do quite a lot of running myself and I was up walking with my family in the forestry last year. They had opened up a new route and I just thought it would make a lovely trail run. We are doing it on the last Saturday in August which was when dad went missing.”

A spokeswoman for Alzheimer Scotland, said:

“We would like to thank the Robb family for pledging to donate funds raised from the Tom Robb Memorial Trail Race to Alzheimer Scotland. Fundraising events of this nature offer us the chance to help raise much needed awareness of dementia and how it affects families every day.

“Alzheimer Scotland is passionate that nobody should face dementia alone and is working hard to create dementia friendly communities to help people living with dementia remain a part of the community. This involves learning a little about dementia and doing very simple and practical things that can make an enormous difference to people living with the condition. In addition we also support research into the use of new technology and are hopeful that advancements in smart devices and trackers will help reduce future risks and give people living with dementia and their families the confidence to live full and active lives."

The Carron Valley Forestry where the race will take place, is situated off the B818 Fintry to Denny road in Stirlingshire.