Charlotte Church's singing brightens up this excessively bawdy update of the Dylan Thomas radio play

Could there be a more Welsh phrase in all English literature than “snouting, velvet dingles”? Previous renditions of Under Milk Wood, the 1954 Dylan Thomas radio play made famous in a mellifluous Richard Burton recording, have gone lighter on one element which Kevin Allen’s new film thrusts at us relentlessly. Not dingles. Sex. Heaving, grunting, mucky oodles of it.

The production notes call this screen version of Thomas’s hymn to Wales – the second to be attempted on film, after Burton’s 1972 one with Elizabeth Taylor – “radically surreal and erotic”. It’s certainly gesturing towards both of those things. Whether the eroticism pays off may depend on personal taste – the bedsheet action in this film is so greasy and feral you could practically catch crabs off it.

The surrealism, though, is more of an open-and-shut case: whacking some vaseline on the lens and festooning your sets with the contents of what looks like a Pembrokeshire community theatre’s prop chest does not automatically produce imagery worthy of the word.

Curiously, two films have been made at once here – one in Welsh, enabling the film to be selected as the UK’s official submission for the Best Foreign Film Oscar. Not since Solomon & Gaenor back in 2000 has a Welsh-language film snuck onto the shortlist.

The Welsh Wood screened to local audiences back in December last year, and soon after on television. Any hope of Oscar glory would require it to be a significantly different beast, though; even performed in the English that Thomas wrote, this production, for all its chutzpah, shambles about nigh-on incomprehensibly.

Sporting a straggly white mane and mutton-chop sideburns, Rhys Ifans does double duty as both the Burton-esque narrator and blind Captain Cat, a washed-up mariner whose dreams are plagued by the barnacled corpses of his drowned shipmates.

It’s an immediate problem for the film that Ifans’s voice, though a little more purely Welsh in intonation than Burton’s, is so lacking in comparable musicality: his somnolent baritone doesn’t exactly send the imagination soaring. Nor, heaven help us, do the luridly overlit visuals, save for a few isolated shots – a baby’s dummy spontaneously turning black in river-water, to take one stray instance.

We take a turn around Thomas’s fictional Llareggub – “Bugger-all” backwards – and meet its assortment of oddball locals, such as the wildly effusive organist Organ Morgan (Aneurin Hughes) and twice-widowed guesthouse landlady Mrs Ogmore-Pritchard (Buddug Verona James).

Charlotte Church sings enjoyably and injects a modicum of marquee charisma as good-time girl Polly Garter. And as the henpecked Mr Pugh, “alone in the hissing laboratory of his wishes” to poison his ghastly wife, Boyd Clack gives a really good performance, twitching and bristling over his soup while trying to project outward calm.

Alas, though, too many of the film’s bawdy inventions and gamey imaginings do little to enhance the spell Thomas cast with words. Far more often, they simply break it.