Imagine any prime minister of recent times having regular trysts with a woman many years their junior and expecting no one to breathe a word.

Or a love-lorn prime minister taking his paramour for regular cosy drives in the official limousine, with its blacked out windows, without a hint of a whisper beyond their inner circle.

Even blatantly meeting at public gatherings or being seated at banquets at the same table as their spouse and no public comment being aired.

Today’s so-called social media would go ape. The ridiculously named X (aka Twitter) would have a feast.

Britain’s “red tops” and the paparazzi who feed them would need look nowhere else for their “news”.

But happen it did. 

And in the midst of wartime when secrecy was paramount.

Which is why Precipice, the latest blockbuster from best-seller Robert Harris, is labelled as historical fiction.  The two genres are combined in a superbly subtle blending  that enhances what is a fascinating and absorbing read.

The outlandish  romantic activities of love-lorn British Prime Minister Herbert Asquith, upon which the narrative is based, are fully supported by the 560 letters this besotted national leader wrote to his lover. 

Yes, they affirm, this flagrant abuse of the Official Screts Act at a most dangerous time in the nation’s history really did happen. But not in the name of treachery or betrayal.

This was simply at the whim of the most powerful driver of all – love, or at least a misguided version of it.

The fictional component comes deftly into play in the responses penned by the object of the PM’s passionate outpourings of the heart. These are cleverly crafted by author Harris in his imagined “voice” of young and attractive sociaite Venetia Stanley.

The only other fictional element is the creation of the dour and dutiful Detective-Sergeant Deemer.  In Harris’s imagination Deemer is seconded from Scotland Yard to the Special Branch under orders to read and report on all the correspondence between the two main players.

He is given his own dingy minuscule cupboard of an office at the Royal Mail’s main sorting office, there to open, read and reseal Asquith’s flood of billet doux to his adored Venetia.

What he reads is scary almost beyond belief as the country’s leader reveals to his lover the innermost discussions and decisions of the government as it hurtles towards the start of the First World War.  

He sees the PM wilfully disregarding all the regulations while riding  roughshod over any need to prevent highly secret information spreading beyond the walls of 10 Downing Street.

Deemer reports to his superiors the contents of  every letter as they are deliberately diverted to his hidey hole of an office. He copies out in laborious longhand every word the PM writes before letters are returned to the nornmal delivery route.

His bosses, those charged with guarding the nation’s secrets,  are on high alert; how best to deal with this aberrant and reckless prime minister?

It’s the sort of intrigue worthy of a George Smiley.

Blissfully unaware that every exchange is being checked and reported on, Asquith shows his loved one telegrams and cables meant for his eyes only. He invites her thoughts and comments on all manner of affairs of state while he remains focussed solely on affairs of the heart.

This flagrant abuse of the strictest protocols even extends to urgent top secret messages of military importance. Asquith seeks Venetia’s opinions on such missives as casually as if they were discussing a dinner invitation.

His letters are a supreme example of the excessively flowery prose of the period, but tinged more and more with an air of frustration and desperation as Venetia’s ardour slowly cools.  Their situation is ridiculous; any future together – despite her lover’s frequent protestations to the contrary – is out of the question.

Greatly flattered at first by being drawn into Asquith’s inner circle – political as well as social – she slowly realises the futility of their relationship.

And there is a war on, which is not going well. 

Other young women of her acquaintance are forsaking the social round for battlefield duties, choosing the mud of Flanders over the frivolity of the Mayfair whirl.

Maybe that is where her future lies, leaving the PM  free to devote his energies to winning the “war to end all wars”.

But Asquith is not one to give in easily when romance is in the air, as numerous other dalliances have shown. He increasses the frequency and ardour of his pleading.

Where will it all end?

Suffice to say Harris paints an absorbing picture of love in high places.  A novel  that ranks with the best of the political espionage genre.