Counterfactual history has to be plausible and offer a tantalising picture of a past at least as interesting as the one the nation lived through. Fortunately for this collection of essays on the best prime ministers we never had, British politics has a rich back catalogue of colourful characters who came close, and life might well have been more interesting under some.
To be honest, there has been more than enough daydreaming about what might have been if R A Butler had fulfilled his destiny in 1957 or 1963; and if Halifax rather than Churchill had received the King's commission at the height of the existential crisis in 1940. Much the same goes for the John Smith premiership of 1997, the least counterfactual of all the possibilities, given that Labour were certain to win then whoever led them. But the idea of Norman Tebbitt succeeding Thatcher in 1989, beating the IRA and walking away from Europe is capable of sending a shiver down the spine, even at this distance of time and reality. Tantalising indeed. As is Oswald Mosley leading, not some fanciful Fascist dictatorship into alliance with Hitler, but a "New Labour Party", as his biographer calls it, that added glamour to Labour's reformist programme of 1945. And I found it difficult to get interested in Herbert Morrison or Austen Chamberlain as alternatives to Attlee and Baldwin.
Of Beckett's long list, I confess that I turned first to the other prime minister Brown – George, who might well have won the 1964 general election and got Britain into Europe slightly earlier. The veteran hack Paul Routledge has been around long enough to have accompanied Brown in his last, sad, election campaign, in 1970. Just as the volatile Brown had a good deal of fun in his career, sadly often to his own detriment, so too does Routledge have a good deal of fun imagining Brown's virtual career as PM, including the order of a stiff gin and tonic as his first executive act, and the "on-off affair" with Christine Keeler, probably the most imaginative flight of fancy of all.
So the past can be unpredictable, but truth can turn out stranger than counterfactual history. By this I mean that no one thought it possible in 1963 that the hapless Sir Alec Douglas-Home would demolish Labour's double-digit poll lead and almost win the Tories a fourth successive term; nor in 1979 that Thatcher would last 11 long years. There was nothing in Blair's past that suggested that he'd end up leading us into a bloody, illegal neo-con adventure in Iraq; and there were few who predicted the abject failures of Gordon Brown, who would have a far higher reputation if he had never made it to the premiership. Perhaps it would have been better if he'd challenged for the leadership in 1992 or 1994 and led Labour to power in 1997, when he might have framed events rather than having to take over in the most unfavourable political and economic circumstances a decade later. Mr Brown's memoirs, I suspect, will have that counterfactual alibi somewhere within them.