He lost control of ITC, which has had a historic importance in the British film and TV business, in 1982 during a fierce clash with the now deceased Australian businessman Robert Holmes a Court.
Now, Lord Grade told guests at his annual lunch at the Hyde Park hotel in London, he would be rejoining as chairman for life. He has always emphasised that he will never retire.
ITC owns many UK classics including Thunderbirds, The Prisoner, The Saint, Secret Agent, Captain Scarlett and The Persuaders. In the Seventies, with its sister company, the Midlands broadcaster then known as ATV, it produced the Muppet Show, Jesus of Nazareth and moved into films - an expensive decision which finally cost Lord Grade control of the company.
While it was not all bad news, Raise the Titanic!, made in 1980 at a cost of more than $30m, (£19.3m) was such a box-office disaster that even Lord Grade remarked that - in a now well-worn Hollywood joke - it would have been cheaper to lower the Atlantic.
PolyGram, the global music and entertainment group which is rapidly expanding into films, yesterday confirmed it has purchased the ITC entertainment group for $156m (£100m). It will form part of PolyGram's filmed entertainment division whose president Michael Kuhn was present at yesterday's lunch.
PolyGram intends to make a new feature film of Thunderbirds, using real actors - there have been no new Thunderbirds programmes made in the past 25 years although the programme is greatly enjoyed throughout the world.
It also plans to make a movie based on The Prisoner, the cult TV series based in the town of Portmeirion, North Wales. Lord Grade said yesterday: "They will have to make the film in Portmeirion and use it again.
"I feel privileged to see what I thought were major series being made into movies." It represents a vindication of his judgement and investment.
In addition, the composer Andrew Lloyd Webber claims that PolyGram - which made the highly successful Four Weddings and a Funeral - is planning to launch a studio in Britain to make musicals.
Mr Kuhn said Lord Grade was returning to the company because he had tremendous contacts in the industry. He said they planned to sit down with Gerry Anderson, who devised Thunderbirds, to start afresh. "It's a wonderful area but it's been in limbo for many years but now the ownership [of ITC] is sorted out we can do something. We found there is an incredible fan club for the existing programmes but it takes thought and care."
Stewart Till, president of PolyGram filmed entertainment international, which operates from the UK, said: "the Flintstones, the Addams Family and Batman show that you have a huge head start if you make movies from known characters and stories. Success isnot guaranteed, but there is always the next generation to interest.
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