Channel 4 has denied that drama series Utopia wrongly suggests Conservative MP Airey Neave was killed by the Government.
Neave was murdered by a car bomb planted in the Palace of Westminster by the Irish National Liberation Army in 1979.
The second series of Utopia, which will be shown from tonight, features genuine footage of the incident.
The new series of the drama portrays Mr Neave being killed by a secret MI5 cell.
His youngest son William (60) said: "I am upset and I would dearly like to protect my father's reputation from lies and fabrication. It seems that when somebody dies, people can say whatever they like. We would love to stop it from airing."
In the first episode Mr Neave – played by Tim McInnerny – is depicted as a heavy drinker, it was reported.
"I don't know why Channel 4 would want to make such sensationalist claims when they are just not true," Mr Neave said.
"The suggestion that my father was a drinker is particularly upsetting and utterly dishonest. After his heart attack in 1959 he gave up drinking altogether. We may well have to take action over this."
But a Channel 4 spokesman said: "The drama series Utopia is entirely fictional, it is a conspiracy thriller about a fictional organisation called The Network.
"Utopia occasionally blends real moments in history with fictional storylines, meaning some events and characters have been adapted for dramatic licence within the context of the series.
"It is not our intention to cause offence and Utopia does not suggest that any other real organisation was responsible for the death of Airey Neave."
He added: "That period in history has been both widely reported and dramatised over the last 35 years and is the subject of many conspiracy theories."
Utopia returns with a double-bill over two nights tonight and tomorrow night.
Airey Neave was a confidant and right-wing mentor to Margaret Thatcher and became one of her closest advisers. Conspiracy theories have long circulated about Neave's murder. Former Ulster Unionist MP Enoch Powell blamed the US and MI6 at different points. Some theories suggest Neave was being lined up as Northern Ireland Secretary and killed as he was a keen integrationist and took a tough security line. Others suggest he was about to shake up intelligence services and wanted to prosecute some officials for corruption.