Eighty-five per cent of the adult population tunes in to radio. The most recent JNLR survey shows some 58 per cent listen to a local station, while 24 per cent listen to RTÉ Radio 1.

As Newstalk goes national, media specialist Ciaran Cunningham, points out "the cake remains the same size". "RTÉ Radio 1 is always going to be the radio of record," says Cunningham, chief executive of media agency Carat Ireland, "but it's essentially a 45-plus station. Newstalk has been attractive to advertisers in Dublin because it has been appealing to the more affluent thirtysomethings."

But will that be the same when it goes national? The main battlegrounds are the news and current affairs-driven morning and evening "drive time" slots. When Newstalk goes national, this is how they will look:

MORNING

(Morning Ireland, RTÉ Radio 1, 7-9am versus The Breakfast Show, Newstalk, 6.30am-9am)

Verdict: Elaine Geraghty says Newstalk's The Breakfast Show, which has a half-hour start on RTÉ Radio 1, will deliver more news in a snappier format. Business news will feature strongly and there'll be vox pops and text polling. The show's presenters are Ger Gilroy, who presented the station's popular Off the Ball show and who doesn't yet sound entirely confident discussing current affairs, and Claire Byrne, the TV3 newsreader, who won't be available to the station for its national launch on Friday.

It's going to be an uphill battle; they're up against RTÉ's experienced team, whose interviews regularly set the talk agenda for the day on the State broadcaster's most listened-to show.

EVENING

Drivetime with Mary Wilson, Drivetime Sport with Des Cahill and Drivetime with Dave, RTÉ Radio 1, 5-8pm; The Last Word with Matt Cooper, Today FM, 4.30-7pm; The Right Hook, Newstalk, 4.30-7pm.

Verdict: Both commercial stations start earlier than RTÉ Radio 1, which has carved up its evening into three segments and is sports dominated. Newstalk's biggest threat will be Matt Cooper, whose programme has settled down into a successful formula.