International superstars Clannad and Enya back home in Co Donegal for three Brennan family concerts for the Earagail Arts Festival - surely not? Martin McGinley rubs his eyes

The time has come for me to go/I bid you all adieu/The open highway calls me back/To do these things I do/And when I'm wandering far away/I'll hear your voices call/And please God I'll soon return unto The Homes of Donegal

They're back, and for another big night in the long musical history of the Brennans. There are three generations of the family onstage, singing like troopers, and a crowd of 700 people are on their feet swelling the sound of Master McBride's classic song of Donegal.

What has just happened in the Clanree Hotel in Letterkenny has been remarkable in itself. Clannad, the full line-up together for the first time in 15 years, have delivered a brilliant set studded with highlights from their long back catalogue, and have received a series of standing ovations.

The patriarch, Leo Brennan, has to follow that and top off the night. And what a finish - from the moment he walks onstage, resplendent in snazzy suit and bow tie, at ease and straight as a reed at 79, the occasion is in the hands of a master.

"My father used to say the best way to entertain a crowd is to let them entertain themselves," Leo often remarks, and he does just that by playing Granny's Old Armchair, Brennan on the Moor and finishing with The Homes of Donegal.

It's a long way from the Academy Awards and the Grammies, but for the superstars that are Enya and the members of Clannad, these are nights when the roots are showing.

Leo, a lifelong entertainer born into a travelling music hall troupe, says he never felt so much at home on a stage. "I wallowed in it," he says. "The old hound for the tarred road." Leo's wife, Baba - who joined him on stage for a wonderfully schmaltzy version of Have I Told You Lately That I Love You (Elvis or Gene rather than Van or Rod) - is a music teacher, choirmistress and arranger. The Brennans have music in the blood.

The idea of bringing the family together as part of the Earagail Arts Festival has been around for a while, but it's a more difficult assignment than most.

Enya is one of the best-selling female singers ever, and fabulously wealthy as a result. However, more than 20 years into her spectacular solo career, she has yet to play a full-scale live gig. She has the trappings of a superstar lifestyle, including the castle in Killiney and the occasional stalker.

Clannad, a ground-breaking group with album sales also running into millions, haven't had their full line-up on stage since around 1990. There was the lingering whiff of a row in the camp, from when Enya famously left the band in the early 1980s. Despite these apparent obstacles, there it appeared in this year's Earagail Arts programme - three events marking the Brennans' contribution to music in Donegal and well beyond, under the title "Oidhreacht" (Legacy).

For stargazers, the only question was: would she or wouldn't she? Donegal, noted for a relaxed attitude to fame, just looked forward to three good nights.

The issue of Enya's contribution was settled on the very first night - the concert by her mother Baba's choir Cór Mhuire in St Mary's Church in Derrybeg. The programme noted simply that the five Brennan sisters - Moya, Deirdre, Enya, Olive, agus Brídín - were to sing three hymns. There was no fanfare when Enya arrived up the aisle with her sisters midway through the concert. As rare superstar appearances go, this gave new meaning to the term "low key".

They sang Pie Jesu, Close to You and Alleluia, with plenty of the fabled ethereality and layered harmonies. It was very much in keeping with the choir's entertaining programme, and this was hardly surprising. Enya herself still contributes to the choir's arrangements - sometimes by text message if they're in a hurry, according to Baba.

The concert gave a broad hint of one of the major influences on the music of Enya and Clannad - church music and choirs. When the Brennan family was growing up in the early 1960s, Saturday mornings meant a trip to Derry for voice training with the legendary James McCafferty, who also taught the likes of Feargal Sharkey and Dana, and whose choirs toured outside Ireland.

Of course, the Brennans also have more exotic musical links. Leo's parents were both music hall performers; his father played piano and his mother played drums. Their Connacht Concert Company travelled around doing variety shows featuring sketches, comedy and music items. Leo started in the business in 1939, when he was in his early teens.

"I'm still singing the songs my dad taught me in those years. When I'm playing in Leo's , I tell the stories of those songs, songs about food, like The Cucumber Song, or one of my favourite titles, You Can Muck About With Brussels Sprouts But You Can't Muck About With Love.

"I'll sing at the drop of a hat. I know thousands of songs, and there's thousands of songs I don't know I know and I know them anyway!"

Leo led the Slieve Foy Showband for many years, but as the small dance hall scene passed on, he bought what became Leo's Tavern outside the Co Donegal village of Crolly in 1968. Locals told him he'd be closed in six months, but he had two secret weapons - his own talent as an entertainer, and the talent of his and Baba's nine children.

Leo entertained in the pub as a singer, accordionist and saxophonist practically seven nights a week, and over the years became the undisputed king of the bus tour. As the children grew older, they started serving behind the bar and doing their own party pieces on stage. Most of them knew some piano and guitar, as well as being able to sing. They drew on the rich heritage of music and song in the Gaeltacht and also updated it, with Irish language versions of songs by the likes of Joni Mitchell and The Beach Boys.

In 1970 Clannad won the Letterkenny Folk Festival competition and a recording contract. They were on their way.

"Visitors come here from all over the world - Japan, France, Germany, the United States, every nation - to see where it all began," says Leo. "And indeed there's not much to see, up the main street and down the same street. It's hard to believe it all started in this wee corner, the family pulling pints and singing in Leo's. Now they're singing all over the world, and Leo's still stuck in the corner!"

By the second concert of the series, Enya was off again to Japan, but the concert in Letterkenny highlighted the depth of talent in the family. The reformed Clannad were superb, polishing up gems such as Níl sé'n Lán, In a Lifetime and Harry's Game, the song that first brought them international success back in 1982.

Five grandchildren took the stage for a traditional set, a sign that the Brennans' musical tradition won't end with the current mob.

The albums are still tumbling out; Enya is apparently under pressure to deliver a new one by Christmas. Moya and Brídín also have new solo recordings on the way. Moya's last album, Two Horizons, got a Grammy nomination in the New Age section. Pól and his partner, Tara Ní Bhroin - who played an excellent short set showcasing Tara's considerable vocal talent - are also working on a release. There's also talk of something more from Clannad and, as he approaches his 80th birthday in September, Leo is still playing regularly in the pub.

Sunday night was the pub's night, with a jazz knees-up from Paddy Cole and his band and Leo on accordion. And just to crown it all, Leo and Baba were also granted the Freedom of Donegal at a civic reception in Lifford during the week.

The Brennan series has been a great success for the Earagail Arts Festival, and something special for the family. It's been particularly significant for Leo and Baba.

"This has been the highlight of our whole lives," says Leo. And considering we're talking about the Brennans, that's really saying something.