Generally known in the chess world as 'Jim' Plaskett, he has written nine chess books and also one quasi-autobiographical one, Coincidences.For some years in the 1990s he was chess columnist at The New Statesman.

He appeared unsuccessfully several times on Who Wants to Be a Millionaire?, and then drew on his experiences to write a defence of Charles Ingram, his wife, Diana, and Tecwen Whittock, who had been found guilty in April 2003 of conspiring to help Ingram win the £1 million top prize by coughing to signal the right answers.

This essay led to an article by Bob Woffinden in The Daily Mail of October 9, 2004 - Is The Coughing Major Innocent?, and also prompted a reconsideration of the case in The Guardian Comment is free blog on July 17, 2006 from Jon Ronson - Are the Millionaire three innocent? Woffinden and Ronson had both been initially sceptical.

Plaskett may also be heard at Episode 29 of The Pod Delusion podcast being interviewed by political blogger, Mark Thompson, who was himself led by Plaskett´s essay to take an interest in the case of The Millionaire Three.

He has also expressed his support for Jeremy Bamber who, in October 1986, was convicted of murdering five members of his adoptive family and sentenced to life imprisonment, and for the exoneration of James Hanratty and his conviction for the A6 murder of 1961.

Plaskett finally got into the hotseat on January 21, 2006, becoming the second person to reach £125,000 without using any of his lifelines en route to winning £250,000. He was accompanied by friend and fellow Grandmaster Stuart Conquest.

Plaskett also organised and led a 1999 National Geographic expedition to Bermuda to follow up reports of "Octopus giganteus" near the island, but was unsuccessful in filming it.

Karl Shuker, another Briton with an interest in both cryptozoological expeditions and unusual phenomena, had previously reached the same £250,000 figure when a contestant on Who Wants To Be A Millionaire?.

Plaskett's brother, Allan, invented the snickometer device which is used globally to assist in umpiring decisions in cricket.