Another side to colourful North Queensland MP Bob Katter has been uncovered -- his family's links with communism.

Renewed interest in the by-gone days of communism in North Queensland follows last week's screening on ABC television of "The Legend of Fred Paterson", a political biography of the only communist elected to any Australian Parliament. Paterson was the state member for Bowen from 1944-1950.

But still hidden among the folklore of communism has been the tale of Mr Katter's father, the late Bob Katter Snr, the former member for Kennedy from 1966 to 1990.

For decades speculation has endured that Bob Katter Snr flirted with communism in his youth and all but joined the Communist Party. Of course, in later life he was a staunch opponent of the movement.

According to Frank Bishop, the North Queensland secretary of the Communist Party from 1953 until it dissolved, there is a story that Mr Katter Snr, who had a clothing store in Conclurry, once went along with publican Jim Boyd to join the Communist Party -- but applications by both were unsuccessful.

"I can't prove it, but Eddie Heilbronn and I had a talk about it once," Mr Bishop said.

He said the late Eddie Heilbronn would definitely have known, but those associated with the episode had passed away. Eddie Heilbronn was a well-known radical communist and a former secretary of the Mt Isa Mines Ironworkers' Union.

But some involvement of the Katters with communism is certain.

Bob Katter Jnr said his maternal grandfather, Stan Horn, was a communist, and a strong supporter of Gerry Dawson, a chairman of the Queensland Trades and Labor Council and a prominent communist.

While he said he believed his father never had been in the Communist Party, he "definitely got on well with communists" in his job as a union representative on the wharves in Brisbane during World War II.

"He most certainly would have been very, very friendly and had a lot of rapport with those people," he said. "My father was one of those blokes who was open-minded. He liked talking to everybody and he was very curious.

"The north is a very radical place and it spawns many radical politicians and very radical politics."

He said that before World War II, the "extreme left" and "extreme right" in North Queensland shared the common political aim of fighting big banks and big corporations.

"Breaking the stranglehold of Lord Vestey and the Colonial Sugar Refinery (CSR) were absolute imperatives if we were ever going to get a go and a right to prosperity for the ordinary Queenslander.

"Once you moved into a cold war situation, the politics changed dramatically"

He said after the war, his father became "a grouper", one of the supporters of B.A. Santamaria. "Their religious mission in life was destroy the communists' control of unions."

But he said there was no doubt his father was a very, very strong friend of left-wing parliamentarian Tom Aitken.

"Tom took me under his wing when I came to State Parliament.

Mr Katter said he remained an admiration of former Labor Premier "Red" Ted Theodore.

"All of these men -- Theodore, Aitken, and Paterson were very well read."

Mr Katter Snr was the Minister for the Army in the McMahon Coalition Government, in 1972, at the end of Australia's involvement in Vietnam.

He died in 1990.