THE FATHER AND SON James and Ben Long have combined their separate skills of novelist and historian to produce an exciting, informative, at times amusing and always readable tale from one of the darkest episodes in English history.

The risk in applying novel-writing techniques to historical material, as they have done, is that you lose the big picture in search of intimacy, but they stay close to their well-researched and documented sources and paint enough of the background to create a narrative that convinces as well as grips.

The background to this story is the Popish Plot of 1678, designed to inflame the nation against a religious minority with foreign affiliations – the Roman Catholics – and thus prevent the accession of a Catholic King, James II. Samuel Pepys, a Protestant, but loyal to James, whom he served as Secretary to the Admiralty, becomes a victim when he is accused of the capital charge of treason and flung into the Tower. From his prison cell this quintessential Sir Humphrey builds and directs an intelligence network and applies a lifetime of Yes, Minister skills to turning the tables on his accusers.

For spy story addicts this is a great tale. Imagination could hardly conjure up such a pack of dodgy-dealing double and treble agents as appear on both sides of this story, single-minded as they are in their pursuit of money, women or social standing.

Pepys’s main accuser is a certain John Scott, swindler, liar, cowardly pirate and serial womaniser. Scott is a man who lives his life by skulduggery of heroic proportions, even managing to acquire the governorship of Long Island by fraud. Although perpetually bankrupt, he contrives more or less simultaneously to be in the pay of the Government, the Opposition, the French and the Dutch, as well as being in touch with Colonel Blood, who attempted to steal the Crown jewels.

Scott’s tradecraft is highly questionable, but at least he has the professional acumen to avoid turning up when Pepys eventually comes to trial, thus causing the whole plot to collapse in a rubble of villainy. He was eventually arraigned for murder and fled, for good, to Norway.

Scott is supported by a cast of forgers, conmen, thugs, perjurers and spies, each pottier than the last. There are numerous gems in the Longs’ account of the tortuous legal transactions that Pepys is subject to. They say, for example, that the term “men of straw” refers to people who hung about the law courts with straw in their shoes to indicate a willingness to give false evidence for cash.

The Plot Against Pepys has its universal point, not to be forgotten in troubled times. Human nature is prone to fear, cruelty, panic, dishonesty, greed and all the rest; but a cool nerve, a clear mind and a determined loyalty can still win against almost any disadvantage – just.

Pepys himself is not the only example in this story. Just as moving is the tale of his clerk, Samuel Atkins, who was also accused, after refusing to tell lies against his master, and, at his own trial, had the presence of mind to call out to the relevant man of straw “Do you know me?” to which the false witness, surprised, replied “No”.

For the interested reader, the intelligence background is authentic. Espionage and subversion were so much a part of domestic and foreign policy making in the 17th century that François de Callières, a diplomat under Louis XIV, could write such music to a spy’s ears as: “There is no expense better designed nor more necessary than that which is laid out upon a secret service.”

The gentle arts of intercepting, opening and reading other people’s letters were part of the stock in trade of every ambassador, and part of the remit of the French Ambassador at The Hague was to organise a group of agents to acquire intelligence from England to enable French policies, which included the covert financing of the Popish Plot, to be managed.

Although Scott was important in the attempt to convict Pepys, he was no more than a bit-part player in the Popish Plot as a whole. The Plot Against Pepys gives only tantalising glimpses of the main actors, principally the Earls of Shaftesbury and Buckingham whose puppet Scott was, and Titus Oates, the accuser in chief, who got his comeuppance when James became king.

But there is enough about the white-hot politics of the period to make the reader want to learn more. Indeed, if we want to interest the young in history, The Plot Against Pepys would be no bad place to start.

It is great fun to immerse oneself in so much wickedness, even better to find that virtue triumphs after all. If you tried to put it into a novel, you would lose credibility – but this tale is true. At it its heart, this story of plots and counter plots contains obvious and fearful echoes to our own times. One of the main lessons that the nation could to draw from the Popish Plot was that mixing religion and politics is potentially explosive, and calls for much restraint if political frenzy is to be avoided and civil liberties and human rights are to survive.

THE PLOT AGAINST PEPYS by James Long and Ben Long

Faber and Faber, £17.99; 480pp

Buy the book here for £16.19 (free p&p)

Pepys’s world

Samuel Pepys was born near Fleet Street in London on February 13 1633, into a well-off tailor’s family.

He was educated at St Paul’s school and won a scholarship to Magdalene College, Cambridge.

After the execution of Charles I in 1649, Pepys became secretary to a relative who was a Councillor of State under Oliver Cromwell. Shortly afterwards, he became clerk at the Exchequer.

He married in 1655, and moved near to the Palace of Whitehall in 1658. Here, at the age of 27, he began to keep a private diary, which he continued until he was 36. He wrote in a form of shorthand that was later forgotten and had to be deciphered.

He recorded events such as the Plague, the Fire of London and the coronation of Charles II, writing in an informal style with close observation.

The diary also describes scenes of politics and everyday life, including civil service committees, debating with MPs, outings with friends, even his affair with a servant.

Pepys stopped writing the diary in 1669 because of poor eyesight. He went on to become Secretary to the Admiralty in 1673, and an MP.

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