Eighty-thousand people bought tickets for the huge outdoor party in the natural amphitheatre below the historic Slane Castle and the concert is also being broadcast on the Internet, TV and radio.

Lord Mountcharles, who succeeded in reviving the tradition of rock concerts in his grounds last year, said he chose Robbie as the top act after his performance at Slane last year.

'Electric atmosphere'

He said: ''I was on the stage when he went on last year. The whole atmosphere was electric. The concert took off. His performance was very much part and parcel of us asking him to headline this years show.''

Slane has been a historic concert venue for 18 years, hosting acts from Queen to Bruce Springsteen during the 1980s.

Slane Castle has been the setting for concerts for 18 years

Slane 1998 proved historic in its own way as it was the last concert that The Verve were to give before breaking up. Even politicians seemed to realise the significance of the event, as Northern Ireland Secretary Mo Mowlam was a celebrity guest.

An impressive line-up including The Happy Mondays, The Stereophonics, Placebo and Gomez are supporting Robbie this year.

Barriers went up to protect the flowerbeds in the tiny village of Slane and the Irish police sent out traffic warnings.

The traffic problems were exacerbated by Armagh fans travelling south to the All Ireland Gaelic football semi-final against Meath in Croke Park, Dublin, on Sunday.

Hundreds of supporters will make the journey over the weekend, as it is the first time Armagh have won a place in the semi-final since 1983.

Over 550 riggers, roadies and engineers have been working on the stage all week.