The actor, who played Bodie in the cult 1970s TV series, alongside Martin Shaw, died in Los Angeles after a five-year struggle with cancer.
His agent said: "He died peacefully at his LA home surrounded by his family. Privacy is asked for at this very sad time."
Julian Bray remembers: "I worked with Lewis Collins on five episodes of The Professionals, which was filmed on location within a 35 mile radius of London, such were the Union rules on overnight allowances for film crews, (they kicked in at 36 miles...) with pickups and links in the studio. Mark One Productions ( part of LWT ) ran a tight ship and the schedule was punishing with many early starts and late wraps."
"One memorable location was a huge country mansion on the outskirts of Welwyn Garden City. Lewis formed a 'close social attachment' with the owners two attractive daughters, and appeared on consecutive mornings of the location shoot, looking out of a different bedroom window .... in true 'Bodie' style, some may say.
"That particular episode also featured a helicopter repeatedly taking off and landing, a 'foreign diplomat' having been saved many times in the process, but deafening the crew... He was always the consummate cool professional, slightly reserved, but fun to work with. 007 Producer Cubby Broccoli clearly missed out by not casting Lewis as James Bond"
The Professionals was a fictional crime fighting unit called CI5.
The show on London Weekend Television and other ITV enjoyed a huge following in the 70s and early 80s.
His co-star Martin Shaw, currently in the West End production of 12 Angry Men, said he was saddened by the news: "We spent a very tough four years together in making the Professionals, and shared in the production of what has become an icon of British television. He will be remembered as part of the childhood of so many people, and mourned by his fans. I send my love and condolences to his family, and the great many who will miss him."
Collins was born in May 1946 in Cheshire, worked as a drummer and later a hairdresser before breaking into acting.
Early work included series such as Z Cars, The New Avengers, as well as The Cuckoo Waltz.
Collins leaves a wife, Michelle - whom he married in 1992, and three sons.
The Professionals is currently being re-run on ITV4.
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