An established festive fixture since their 2001 reunion, the Pogues played to a crammed Evening News Arena in Manchester on Saturday. A rowdy crowd waved Irish tricolours and roared along to such punk-folk classics as Streams of Whiskey and The Boys from the County Hell. No other band has turned alcohol abuse, sickness and the bittersweet pains of diaspora into such lusty, life-affirming poetry.

The sorry state of Shane MacGowan, however, may have been too steep a price to pay. The Pogues frontman turns 49 on Christmas Day, a feat of endurance that many consider on a par with any previous festive miracles.

Much has been written about the singer’s ruinous appetite for drink and drugs over the years, often marvelling at his superhuman survival skills. But in Manchester, frankly, he looked like a badly embalmed corpse. Bloated and pale, he now has Syd Barrett’s thousand-yard stare, Ozzy Osbourne’s stooping shuffle and Brian Wilson’s permanently glazed expression. Pete Doherty, consider this a warning.

Even if we leave aside the distasteful, bear-baiting aspect of watching anybody perform in this condition, MacGowan’s vocal skills have clearly been diminished by years of excess. He could barely carry The Broad Majestic Shannon and A Pair of Brown Eyes, bawling and mauling his own eloquent lyrics into garbled drunken gibberish. Even between songs his slurred announcements sounded like a stroke victim’s. “Just one syllable we can recognise, please!” implored one reveller on the next row.

As is now traditional on these post-reunion tours, MacGowan took a break every three or four numbers, sinking into a shadowy backstage corner while the tin-whistle player Spider Stacey or guitarists Phil Chevron and Jem Finer took over vocal duties. Some of these tunes, notably the impassioned emigration anthem Thousands are Sailing and the Springsteen-esque power ballad Tuesday Morning, only highlighted the focus and energy now sorely lacking in MacGowan.

That said, the singer did sharpen up in the set’s later stages, delivering magnificent versions of Ewan McColl’s Dirty Old Town and Brendan Behan’s The Auld Triangle. The unusual stop-start arrangement of the latter offered a fine demonstration of the band’s exemplary ensemble playing, as did the intricately interwoven melody lines of Rainy Night in Soho.

For the inevitable finale of Fairytale of New York, the guest vocalist Ella Finer sang Kirsty McColl’s part while the entire Manchester congregation joined in a rousing karaoke singalong. Above all others, this is the tune that has given the Pogues immortality. By some bizarre stroke of Christmas magic, it appears to be keeping Shane MacGowan alive too.

Tour continues: Brixton Academy, SW9, tonight