The former full-back had been suffering from vascular dementia, the second most common form of dementia after Alzheimer's disease. The Association of Former Manchester United Players raised funds for the Alzheimer’s Society, a leading dementia charity, at an Old Trafford dinner last week.
Born in Falkirk in 1949, Scottish youth international Kopel joined United as a schoolboy in 1964 and went on to make 12 first-team appearances. He made his debut against Burnley in September 1967, coming on for his compatriot John Fitzpatrick during a 2-2 home draw.
Ten of Kopel's outings came in the 1968/69 season, when the Reds were the reigning European champions with Shay Brennan and Tony Dunne as the first-choice full-backs in Sir Matt Busby’s squad.
Kopel departed to Blackburn Rovers in 1969 and spent three seasons at Ewood Park, before moving to Dundee United in 1972. He went on to make over 400 appearances for the Tannadice outfit, helping them to win the Scottish League Cup twice and becoming a fans’ favourite.
After finishing his playing career at Arbroath, Kopel went on to become assistant manager of the side and later had a spell at Forfar in the same capacity.
Staff at Manchester United extend sincere condolences to Frank Kopel’s family and friends at this difficult time.