Brian Viner: Green army in heaven as the Guinness rains down on Black Velvet

Shamrocks spilt out of buttonholes on St Paddy's Day as electric-green top hats outnumbered tweed flat caps 10 to one

(REUTERS)

When Alan and Caroline Murfin decided to name their folk band Black Velvet, after the Guinness-and-champagne cocktail supposedly invented in 1861 by the bartender at Brook's Club to symbolise the nation's sorrow over the death of Prince Albert, they did not expect quite the liquid baptism they got yesterday. Hired by Cheltenham racecourse to celebrate St Patrick's Day, the Murfins, with their lovely daughter Emma (Miss Cornwall 2004, no less), stood in a corner of the Selling Stakes Arena belting through their impressive repertoire of Irish songs. But halfway through "The Fields of Athenry" they realised that it wasn't condensation forming the droplets which landed steadily on their heads, but the black stuff, which had collected in the gutter on the crowded terrace above.

Only at the Cheltenham Festival on St Paddy's Day could it actually rain Guinness, not that it was quite the day for the Irish, on the track at least, that it had been on Wednesday, when the first six races were won by horses trained in the Emerald Isle and one Kerryman lamented the fact that the Taoiseach had not staked the formidable national debt on an accumulator.

Wednesday's results would "encourage Irish racegoers to travel over to Cheltenham", according to clerk of the course Simon Claisse, but there was precious little sign yesterday that they needed any. Shamrocks spilt flamboyantly out of buttonholes, while tweed flat caps were outnumbered 10 to one by electric-green top hats. And those who weren't Irish, pretended to be Irish. The winner of the Most Quintessentially Irish Gentleman competition, organised by vintage clothing entrepreneur Suzanne Rafferty, plainly hailed from somewhere considerably closer to Didcot than Dublin.

Alongside Ms Rafferty's vintage clothing stall, the women in the Arkle Bookshop claimed to be enjoying their best-ever Cheltenham, with Robin Oakley's history of the Festival the clear front-runner ahead of Ruby Walsh's autobiography, half a length clear of Sir Peter O'Sullevan's Horse Racing Heroes in third. The Arkle Bookshop women are expecting the great O'Sullevan, accompanied by his good friend Lester Piggott, to do some book-signing today, "between 11 and 12 depending on traffic".

As for the human traffic in and around the huge grandstand, it became predictably more chaotic as the afternoon wore on, with the more refreshed punters making increasingly exaggerated detours round obstacles, their steering apparatus lubricated by heaven knows how many pints of Guinness, even at £4.10 a pop.

But the joy of Cheltenham is that racing remains the main event, even more than the drinking, even on St Patrick's Day. That low rumble of excitement that builds into the thunderous Cheltenham roar is truly one of the great sporting sounds, although it was twice punctuated by jeers yesterday, once when the big screen malfunctioned, and again when a man ran on to the track in the closing stages of the Ryanair Chase, waving a banner detailing some grudge against Ryanair, whose CEO, Michael O'Leary, said: "It's a shame if someone was trying to create cheap publicity for themselves." A shame indeed, and only a few cynics in the press room were reminded of the late Oliver Reed complaining about drunkards. Nonetheless, it was an indefensibly stupid act, endangering not only his own life but those of horses and jockeys, and it's hard to imagine the ghost of suffragette Emily Davison finding much kinship with the grinning anti-Ryanair protester, who was dragged off by police and arrested.

The jeering had long given way to cheering by the time the following race, the Ladbrokes World Hurdle, reached its thrilling climax, with Big Buck's and Grands Crus, both French-bred, justifying their status as favourite and second-favourite. Up in the loftier levels of the grandstand, there was particular excitement in the seats sponsored by France Galop, French racing's regulatory body. For all his excitement, Hubert Monzat, France Galop's urbane chief executive, told The Independent over a glass of fine and expensive claret that Cheltenham always makes him "a bit jealous". Apart from the Prix de l'Arc de Triomphe, France has nothing comparable. Yet here at the foot of Cleeve Hill, it all happens again today.