A SCOTTISH father-of-four who lost his wife to a rare, genetic cancer and from which their children are now at risk, has encouraged people to consider leaving money in their wills to cancer research – what he calls his “fifth child”.

Jo Williamson, from Auchterhouse, near Dundee, is starring in a new UK-wide television awareness campaign, highlighting Cancer Research UK’s commitment to life-saving work which is made possible by bequests.

WATCH: Dundee father who lost wife to cancer stars in new TV campaign

The 67-year-old, a retired wine buyer, also features in newspaper and bus stop ads, as well as posters in the charity’s 600 shops across the UK, alongside research nurse Laura Rooney, who is based at the Beatson West of Scotland Cancer Centre in Glasgow.

His wife Sue died at the age of 57, two days before Christmas 2003, after a 10-year battle with a rare cancer known as pheyochromocytoma. It was a hammer blow seven years later when it was discovered that the disease can be caused by a faulty gene.

Doctors said there was a 50/50 chance that their children would also carry the faulty SDH-B gene.

His eldest children – Katie and Jonathan – do not carry it, but twins Jennie Chinembiri and James Williamson, both 38, have inherited it.

This gives them a higher chance of developing cancer and they undergo regular scans to check for tumours. Those that have been discovered so far in the twins have been found to be benign, which means they were not cancerous.

In the moving advert, called I Pledge, Williamson is filmed hillwalking at sunrise on one of the coldest days of the year, encouraging people to promise to leave something in their wills to help beat cancer for future generations.

He appears in the video alongside nurses, doctors and scientists who commit to turn these pledges into new breakthroughs and create new hope. Gifts in wills fund more than a third of Cancer Research UK’s work, helping to turn laboratory discoveries into better treatments for patients.

“My wife Sue was a great family person and our children were absolutely the most important part of her life,” said Williamson.

“We were married for 28 years and there are so many special things we all miss about her.

“I’m fortunate now to have seven grandchildren and I know how much Sue would have loved them too.

“It is so sad that she didn’t live long enough to meet our grandchildren. They bring me so much joy and I would have loved for her to share in that joy.”

Williamson, a Cancer Research UK campaigns ambassador, regularly lobbies politicians to keep cancer at the top of the political agenda and has raised £200,000 for Cancer Research UK and other cancer charities by completing various fitness events, including eight marathons.

His son James, a firefighter in Dundee, has had five tumours removed from near his abdomen and has one large tumour in his carotid artery which is too dangerous to operate on. His daughter,, 12-year-old Abbi, does not carry the faulty gene.

Chinembiri, who lives in Penicuik, has one tumour in her jugular vein and impossible to operate on. Her children Anatswa, five, and Kupa, four, have not yet been tested.

Lisa Adams, Cancer Research UK spokeswoman for Scotland, said: “We hope Jo’s commitment inspires as many people as possible to consider leaving a legacy to the charity.”

Williamson added: “If I have money left to leave in my will when I die then I’ll leave that money to my four children and if you like, research into cancer is the fifth child. I plan to divide everything into five.

“We’ve been fighting cancer as a family for a long time now. I want to help fund vital research into cancer to protect future generations.”