Stuart: A Life Backwards BBC2, 9pm

By his own admission, Stuart Clive Shorter was "the nightmare you frighten your kids with the kind of homeless person you want off your streets". An alcoholic and a heroin addict, Stuart spent most of his anger-filled 33-year lifespan looking half-mad, filthy and threatening in parks and on pavements around Cambridge's city centre.

When Stuart wasn't there, lolling on a flattened-out cardboard box al fresco and being given a wide berth by decent passers-by such as you and me, he was either setting his council accommodation ablaze or he was in prison for various crimes, most of them involving violence. On a day-to-day basis, you wouldn't want to live too close to Stuart (or his lice and his crabs).

Luckily for us all, however, this self-tattoo'd example of the millennial underclass met Alexander Masters, a nerdy young academic who bravely set aside his initial scorn of Stuart - a condescending mix of amusement and suspicion - and decided to become his biographer.

As David Attwood's spell-binding dramatisation of Masters's deftly-unsensational book established, Stuart was certainly easy to judge (guilty most of the time, m'lud), while at the same time being far from easy to like or understand.

The effort to do both of the latter, however, was in the end strangely, tearfully uplifting beyond all measure.

What persuaded Masters to make the effort? Because Stuart offset his manifold flaws with an ability to be wildly funny, carelessly frank and brilliantly childlike in the workings of his ceaseless imagination.

Stuart it was who gave Masters's book its unusual back-to-front format. For no biography of Stuart Clive Shorter was going to turn out as some conventional, weak-kneed wallflower.

No, his biography was going to be a blockbusting money-maker, in the headlong manner of a crime thriller. For it was going to provide the riveting answer to a riveting question, that question being Stuart's own: "What murdered the little boy I was?" What had killed his youthful innocence and promise? What had turned him bad?

Scorning any self-pitying impulses to blame everyone else for his ills, Stuart eventually identified his own over-developed rage as the culprit. Sure, his childhood had been blighted by heartless bullying and years of monstrous sexual abuse.

But so had other people's, none of whom had followed Stuart's vengeful path in choosing to headbutt and knife-fight their way through life.

Over the years, he had enjoyed letting himself being overtaken by sociopathic rages as he confronted his tormentors. His problem lay in being unable or unwilling to resist the urge to lash out.

As the sympathetic and admiring Alex, Benedict Cumberbatch wore the right look of pained decency. Tom Hardy portrayed Stuart - a life-long sufferer from muscular dystrophy - with a restless grace and fizzing, foam-flecked energy from which it was impossible to avert your gaze.

Watching him was to be arrested by a crazy, shambling cross of Johnny Rotten, the Hunchback of Notre Dame and Harold Steptoe.

You couldn't help but be transfixed as Stuart employed the baroque barrow-boy's speech patterns of Kenneth Williams to express his constant wonder and outrage at the world.

There was that time Stuart had attempted to cut 'is neighbour's 'ead orf wiv a bread knife. "If 'e 'adn't-a moved, I'd-a got 'im, too," Stuart insisted with pride.

And what of his disarming initial admission to some of Alex Masters's upper-crust chums when invited to spend a weekend at their sixteenth-century mansion house? "Alex 'as told you I'm an alcoholic? I'm also a Schedule One offender and a thief - but I won't cause no trouble."

Being gripped by Stuart: A Life Backwards was no trouble at all.