If you’d tuned in to the BBC’s Daily Politics show this lunchtime you would have been instructed by Anita Anand and Andrew Neil to ‘let your counterfactual imagination run wild!’ and steel yourself for a journey to a political fantasy world.

Francis Beckett, contributor and editor of The Prime Ministers Who Never Were, appeared on today's show to discuss his latest book and the interview started with a nostalgic saunter down memory lane with a video clip showing the smiling Tebbits, Kinnocks, Clynes’ and Butlers of bygone years, while John Lennon’s Imagine played fittingly in the background.

When asked who his favourite almost-Prime-Minister would be, Francis plumped for J.R. Clynes, who came within a whisker of defeating Ramsay Macdonald for the Labour leadership in 1922, but not before first considering the cases of John Smith, Dennis Healey and Norman Tebbit, all of whom came very close. Had Clynes become PM, Beckett explained, Labour would most probably have won the 1925 General Election, and we wouldn’t have had to wait until 1945 to see a reforming Labour government with an overall majority. In The Prime Ministers Who Never Were Phil Woolas, who penned the chapter on Clynes, even goes so far as to envisage him scrapping the Versailles Treaty and averting the First World War altogether. Just imagine...

This book of political counterfactuals is not merely a collection of dissatisfied wishful thinkers irritated that their favourite political figures were, for whatever reason, denied what was rightfully theirs, with ensuing adverse affect for the country in general. As Beckett explained, it’s a much tighter work than that: to be admitted to the club of almost-Prime-Ministers, there had to have been a moment where the position was definitely within reach – for this reason, Guest of the Day Mark Serwotka’s suggestion of Tony Benn doesn’t quite qualify.

And according to the expert, who came the closest to seizing the title? Francis reckons Rab Butler, who had two shots at the position – once in 1957 and again in 1963. But why not make up your own mind on the subject: The Prime Ministers Who Never Were is available from the 24th March, priced £14.99