A grandfather is showing no signs of slowing down after hitting 70 as he gears up for a year packed with running.

Eastern Daily Press: Stewart South with his sons Joel and Oliver who both required kidney transplants as teenagers. Photo: Courtesy of Stewart SouthStewart South with his sons Joel and Oliver who both required kidney transplants as teenagers. Photo: Courtesy of Stewart South (Image: Archant)

Stewart South, from Blackborough End near King's Lynn, is in the final throws of his training for the Norwich half marathon this month just weeks after donating his 100th pint of blood.

He is fundraising for kidney research after both of his sons needed a transplant as teenagers.

He said: 'My two sons both lived healthy and active lives. Joel was a super-fit, sports-mad teenager and it was not until he had to get a doctor's certificate to say he was fit enough to take up amateur boxing did anything appear to be wrong.

'He was referred to the NNUH in 1997 and they diagnosed him with the start of kidney failure.'

Eastern Daily Press: Stewart South donated his 100th pint of blood at Wisbech Fire Station last month. Photo: Courtesy of Stewart SouthStewart South donated his 100th pint of blood at Wisbech Fire Station last month. Photo: Courtesy of Stewart South (Image: Archant)

Stewart's wife Alison was identified as a carrier for a hereditary condition called familial nephritis and their other son Oliver was told he too might be affected.

Joel was placed on dialysis and ended up in critical care in a coma for five days.

In 1999 Stewart donated one of his kidneys to his son, and Oliver, who went into kidney failure several years later, received a kidney from an anonymous donor.

'After the transplant I wanted to regain my fitness and give something back for all the excellent treatment we had,' he said.

Stewart has completed the Three Peaks Challenge, several marathons including London and New York and raised more than £12,000 for Kidney Research.

After retiring from his PR role at the Environment Agency he has picked up the gauntlet again and this year he has decided to pull out all the shops.

As well as the Norwich Half Marathon this month he will be running the King's Lynn GEAR 10k, the Edinburgh and Amsterdam Marathons and regular Parkruns.

He said: 'I want to share my story as I would like to think my challenges at my age might inspire some other EDP readers to get up and do their thing.'

If you would like to sponsor Stewart visit his JustGiving page at http://uk.virginmoneygiving.com/StewartSouth