Withnail and I is a melancholic masterpiece and one of the funniest British films ever made. For its one-liners alone Bruce Robinson's sweary caper is rightly regarded as a classic: "We've gone on holiday by mistake". "Don't threaten me with a dead fish". "We want the finest wines available to humanity, we want them here and we want them now". These droll zingers are fired off at such a clip, multiple viewings are required to savour them in their full glory.

Yet as Robinson's semi-autobiographical account of two starving actors adrift in late Sixties London turns 30, it is important to note there is more to Withnail than bleak quips and explosive expletives. This is a rare chuckle-fest with a soul and a profound insight into the human condition.

Withnail is indeed a far deeper affair than its cult status among boozy undergraduates might suggest. The film spins the darkly hysterical tale of a pair of wine-fuelled miscreants – the eponymous Withnail (Richard E Grant) and his unnamed sidekick (Paul McGann, identified as "Marwood" in the script) – who swap their dank Camden flat for a rejuvenating break in deepest Cumbria.

But it is furthermore a treatise on friendship, a meditation on the agonies of adulthood and a eulogy for the death of the hippy dream. Withnail and I has a funny bone but also a raw ache at its centre, which is perhaps why it continues to speak to audiences. Here are 10 reasons Robinson's shoestring curio has a claim to the title of greatest British comedy of all time.