The duo dubbed their own characters when they were in Los Angeles last month for a Swell Season gig.

Glen and Marketa will be busking outside a Grafton Street boozer run by Kenneth Branagh who’s actually from Belfast and sounds English but, hey, let’s not split hairs.

“Homer and Grandpa go to this bar that Grandpa went to 40 years ago and it was the happiest night of his life,” reveals Simpsons Executive Producer Al Jean. “They get drunk, they buy the bar, and then they find, as it turns out, in Ireland, pubs aren’t so popular anymore because you can’t smoke in them, so they’re really up a creek.”

Meanwhile, it’s been confirmed that a stage version of Once is to premiere on Broadway in 2010. The men overseeing the project are John Hart Jr., Frederick Zollo and Jeffrey Sine, the American film and theatrical producers whose collective CV includes Mississippi Burning, Quiz Show, Boys Don’t Cry, Chicago and The Who’s Tommy.

According to Zollo, Glen and Marketa will both be involved in the treatment, which is being designed for “intimate” 1,000-seater theatres.