“Your conscience is my enemy,” laments a weary campaign manager as presidential hopeful William Russell stubbornly refuses to drop the bombshell that would not only clear his path to the White House but end his opponent’s career in one fell swoop.

With mud-slinging now the hallmark of any (US presidential) election – Trump’s vitriolic smear campaign comes to mind – The Best Man, Gore Vidal’s 1960s vivisection of a scrupulous politico’s wrangle with his conscience makes quite an intriguing proposition.

The ballsy drama charts former Secretary of State Russell and his populist opponent Joseph Cantwell’s fierce bid for the presidential nomination of their unspecified party, and the all-important endorsement of ex-president Hockstader – who is keeping his cards close to his chest.

As the race heats up, the campaign gets personal. Nakedly ambitious Cantwell threatens to release old medical records revealing Russell’s stress-related breakdown and possible manic-depressive tendencies. Not only that, but to expose his marriage of convenience as the thinly-veiled sham it really is. When Russell’s resourceful campaign manager suggests a counter-offensive, he wrestles with the prospect of compromising his moral standards to play, and win dirty. The true genius of Vidal’s political tug-of-war is its uncanny power to explode preconceptions of morality and rectitude.

While Russell is, on the face of it, the rotten of the two – an incorrigible philanderer shamelessly running on a family-man ticket – he musters up far more moral fibre (and political nous) than his opponent: the living embodiment of the stand-up all-American husband and father. Private and personal personas blur to reveal a far more nuanced and complex picture. The best man for the job may not be the ‘better man’.

Martin Shaw is a force to be reckoned with as righteous Russell, who against all evidence to the contrary, is a man of principle – one willing to sacrifice everything, even his own ambitions at the altar of morality. Fahey is a worthy opponent as hot-headed Cantwell. Dangerously blind to his own flaws,his impulsive strikes and ill-advised rants are ultimately the instruments of his downfall. But Jack Shepherd steals the limelight as paternalistic ¬– and closet misogynist – ex-President Hockstader. The fact that he speaks some of the play’s sharpest one-liners certainly gives him quite the leg-up. But Shepherd’s kudos are all his own, and he succeeds in injecting warmth and old-school charm to the shady statesman.

These days, of course, Russell would no doubt bite his campaign manager’s hand off for a speckle of dirt on his rival. Regardless, imagining a man stubborn and strong-minded enough to play fair is refreshing, and oh-so needed. Vidal’s romp is sure to restore your faith in humanity and the political arena (until the next time you flick on the news, that is). – MARION SAUVEBOIS

The Best Man runs at the Theatre Royal bath until Saturday, October 14.