On an autumn day in 1680, the 50-year-old Charles II charged Samuel Pepys with an unusual task. Over two three-hour sittings, one on a Sunday evening, the next the following Tuesday morning, the king related to him in great detail his personal recollections of the six weeks he had spent as a fugitive after the Battle of Worcester in 1651. It was nothing less, in the words of Arthur Bryant, than ‘the most romantic incident in the history of the English throne’. As sovereign and secretary settled down (a scene that is surely a gift for a future scriptwriter), Charles commenced his story: ‘After that the battle was so absolutely lost as to be beyond hope of recovery, I began to think of the best way of saving myself.’

Charles Spencer’s latest book, To Catch a King, does for us exactly what Charles II intended when he asked Pepys to commit his story to paper: ensure that this most extraordinary episode is never forgotten. And what a story it is. Two years after the execution of Charles I, the young Charles II sacrificed the very principles his father had died for to do a deal with the Scots, accepting Presbyterianism as the national religion in return for being crowned King of Scots. His arrival in Edinburgh prompted the English to invade Scotland in a pre-emptive strike. This was followed by a Scottish invasion of England. The two sides finally faced one another at Worcester in September 1651. After being comprehensively hammered on the meadows outside the city by Oliver Cromwell’s army, the 21-year-old king found himself the subject of a national manhunt, with a huge bounty on his head. Over the following six weeks he managed, through a series of heart-poundingly close escapes, to evade capture before finally making it to safety in France.

One of the joys of this book, a result not least of its use of Charles II’s own narrative as well as those of other contemporaries, is just how close the reader gets to the action. The day-by-day account of the fugitives’ doings provides delicious details: the cutting of the king’s long hair with agricultural shears, the use of walnut leaves to dye his pale skin, Joan Penderell dressing the royal blisters and drying his sodden shoes with coals, and the day Charles spent lying on a branch of the great oak tree in Boscobel Wood as the Parliamentary soldiers scoured the forest floor below. Spencer draws out both the humour – such as the preposterous refusal of Charles’s friend Henry Wilmot to adopt disguise on the grounds that it was beneath his dignity – and the emotional tension when the secret of the king’s presence was cautiously revealed to his supporters: ‘I am commanded to be free with you, and to let you know that the King is at Colonel Wyndham’s house.’

The adventures of Charles II after losing the Battle of Worcester must rank with the British Expeditionary Force’s experiences at Dunkirk as one of the supreme examples of the British talent for recasting humiliating defeat as miraculous victory. The uncomfortable truth was that while almost everyone in England had been appalled by the execution of Charles I, they had not welcomed the arrival of his son with the Scots army, but had instead firmly bolted their doors. This was partly because he rode at the head of what felt like a foreign invasion force and partly because after almost a decade of civil war people were desperate to avoid it beginning again. This makes it all the more interesting that Charles II himself loved the story so much ever after. As well as retelling it to anyone who would listen, causing eye-rolling among courtiers, he set in train a slew of initiatives to memorialise it. There was to be a new order of chivalry, the Knights of the Royal Oak. A series of enormous oil paintings celebrating the episode were produced, including a two-metre-wide canvas of Boscobel Wood and White Ladies and a set of six similarly enormous paintings of the king on the run. On the ceiling of his bedchamber at Whitehall, in 1660, John Michael Wright painted a flying squadron of putti carrying an oak tree to the heavens. It is hard to imagine many other sovereigns celebrating their lowest ebb so enthusiastically, or indeed pulling off such an escape in the first place.

Charles Spencer is the perfect person to pass the story on to a new generation. His pacey, readable prose steers deftly clear of jarring modern idioms and coasts elegantly through the great tale. He has even-handed sympathy for both the buccaneering fugitive and the fierce republican regime that hunted him and he succeeds in his desire to explore far more of the background of the story than previous books on the subject have done. Indeed, the opening third of the book is about how Charles II found himself at Worcester in the first place, which for some will be reason alone to read To Catch a King.

The tantalising question left, in the end, is that of what it all meant. Would Charles II have been a different king had these six weeks never happened? The days and nights spent in barns and priest-holes, servants’ halls and pubs must have had some influence on his character. Did the need to assume disguises, to survive on wit and charm alone, to use debonair trickery and subterfuge to escape from tight corners help form him? This is the one area where the book doesn’t quite hit the mark. Instead it falls into a cod characterisation of Charles II in his final years as a gluttonous boozer in thrall to a French mistress who had been sent by Louis XIV to spy on him, which doesn’t do justice to the man (neither is it accurate), or to the complexity of his mercurial character. But this one niggle aside, To Catch a King is a cracking read, and those who come to it knowing little of the famous tale will find they have a treat in store.