A letter sent to Kettering by a friend of the player, who starred for the Poppies and helped them to reach the 1979 FA Trophy final at Wembley before signing for Posh in the same year, confirmed Kellock has been struggling with ill health.
In his letter, John Paterson said Kellock, who is now 68 and still lives in Kettering, has still been working despite his health issues.
And Paterson is now seeking help from the fans Kellock, who also played for the likes of Wolverhampton Wanderers, Southend United and Halifax Town, used to delight with his performances.
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In his letter, Paterson wrote: “I am writing to you about a friend of mine Billy Kellock who was a significant football player for Kettering Town in the 1970s and again in the 1980s.
“As I am sure you will know this was a time when players did not earn anything like their counterparts these days.
“He had a major battle with level four throat cancer a few years ago and against all odds he overcame the cancer.
“Billy now works as a painter and decorator as he has done for the past 10 years or so.
“Sadly his health has deteriorated again recently having been diagnosed with double pneumonia and he is too proud to ask for any help.
“He is still attempting to work when he really needs to rest up for a couple of months to regain some weight and have the strength to continue.
“He has lost a considerable amount of weight recently and this is making him too weak to be able to ward off his illnesses.
“We are trying to do everything we can to help him mentally and financially in order
that he can take as much time off work as he needs to get well again.
“I know that Billy was and still is a very popular player amongst the older Poppies fans and I have seen it with my own eyes when my neighbour met Billy at a summer barbecue at my house last year.
“My neighbour has been a lifelong Poppies fan and was completely star struck when he met Billy for the first time.
“Billy is a proud man and would never ask for help but I am asking on his behalf because I know he really needs our help at the moment.
“If there is any amount you can spare to help towards Billy’s living expenses so he can take a much needed break I know this will be really appreciated. Hopefully when he gets better, Billy will have the strength to thank you all!”
The GoFundMe page has already raised over £1,000 towards a target of £2,500 and donations can be made by visiting the site www.gofundme.com/f/kettering-footballing-legend-needs-help