Jeremy Thorpe: Who was the Liberal Party leader and what led to his spectacular fall from grace?

To understand how big a deal Jeremy Thorpe was some four decades ago, it is helpful to transplant him into the modern day.

Imagine then a Liberal political leader who burst onto the scene with even more verve and energy and impact than Nick Clegg did in 2010, if you can cast your mind back to Cleggmania. And did so with the result that he almost single-handedly denied either main party a majority at a general election.

Imagine too a man with the charisma and style of a character such as Nigel Farage (though far from sharing his politics). Top that lot off with the ready wit and celebrity of the likes of Boris Johnson. He was married to an ex-wife of the cousin of the Queen and he had once toyed with the idea of wedding Princess Margaret. That was Thorpe.

Now imagine someone combining those talents and of that stature in national life being put on trial at the Old Bailey on a charge of conspiracy to murder.

Murder, that is, of a former lover after he had rather callously ended a homosexual affair. And a trial in which intimate letters to “bunnies” and references to Vaseline and “biting the pillow” reached the public domain. Plus a Great Dane shot dead by accident on Dartmoor.

Such was Jeremy Thorpe. In the British general election of February 1974, Thorpe took his tiny Liberal Party to the very edge of government, almost holding the balance of power in a hung parliament. There was as strong chance that Thorpe himself might be asked into a coalition government with the Conservatives as Foreign Secretary or Home Secretary. He was 44. From there? Maybe Number 10 itself.

Instead he had had to resign from the party leadership, lost his seat at the 1979 election (his trial was suspended so that Thorpe could campaign), wound up in court.

In the view of many, only an indulgent summing up by a senior judge saved him form a lengthy sentence at her majesty’s pleasure. In modern terms, you’d call it an establishment plot to get one of their own out of trouble; Thorpe might have called the allegations against him “fake news”; it was certainly sleaze before the term became synonymous with British parliamentary life.

Thorpe, unusually, was to be denied the usual honours and respect bestowed on ex-leaders – knighthood, a seat in the Lords, elder statesman status at party conferences.

The Thorpe trials - there had been a sensational earlier committal hearing in Minehead - gripped the nation and periodically dominated the newspapers, whose only worry was how much of the explicit sexual details to carry in their coverage (the broadsheets were more salacious than the tabloids).

The judge’s summing up was so comically biased it became the basis of a famous sketch by Peter Cook. Gay liberationists, and others, would wear T-shirts with the slogan “Bunnies can go to France”, a reference to one of Thorpe’s letters to his lover.

The Liberal Party was a laughing stock, and was polling lower than the neo-Nazi National Front. It was quite the fall from grace.

Thorpe was a gifted, gifted politician and something of a prototype for the modern media politico, having himself had a short career as a TV journalist and a talent for pulling clever stunts, such as touring marginal coastal constituencies in the then-white hot Hovercraft, a fittingly advanced and modern piece of machinery for such an advanced and progressive politician. (It broke down, though).

His clothes were something of a throwback to the Edwardian era and Thorpe was always, from his student days knocking around Oxford right up to his final years of frailty under the ravages of Parkinson's, a dandy, the trademark brown Trilby and waistcoat plus watch chain as familiar to the public as Harold Wilson’s pipe.

He was a genuine wit and fine mimic, taking off a Devon farmer as readily as the prime minister, Ted Heath.

He could get up in Parliament and wound another prime minister, Harold Macmillan, after a panicky reshuffle with the clever line that “no greater love hath man than this, that he lay down his friends for his life”.

He was also - despite his chequered private life and, well, the conspiracy to murder business - a man of high principle. In the days before equality and respect, he campaigned for laws to ban race discrimination and he was a quiet supporter of gay rights in an era when all homosexual conduct by men, even in private homes, was a criminal offence.

He fought for European unity, for immigrants and refugees, for the United Nations and the Commonwealth thoroughly advanced and against colonialism.

For many, myself included, Thorpe was a political hero, easy to admire for style and for substance.

Had he been born in, say, 1989 rather than 1929, I cannot see that what befell him and his boyfriend Norman Scott would have occurred.

He would not have had to live a lie, his private life would not have been a crime, his first marriage troubled and he need not have ever wondered aloud, or conspired, about how much better of the world would be if a certain male model wasn’t around any more.

Thorpe was once the most popular politician in the country but soon to be the most embarrassing.

Had the climate of the times and the temperament of the man been a little different - Thorpe might have done the country, as well as his party and himself, much good. That is the Thorpe tragedy.

Episode one of A Very English Scandal airs on BBC One at 9pm on Sunday 20 May