One of my secret fantasies came true earlier this year when I boarded a flight home from Heathrow and installed myself in a seat by the window. The first thing I noticed was that the middle seat was empty, but that wasn't the fantasy. No. Exciting as it is these days to have elbow-room on a plane, that discovery paled to nothing when I glanced at the aisle seat to see who I was travelling with. And there, like a vision, was Mairéad Ní Mhaonaigh, writes Frank McNally.
It is only proper to say at this point that there also - in the seat opposite her and slightly less like a vision - was Mairéad's husband, Dermot. Lovely as he is, Dermot was never part of my fantasy. But in common with many frequent fliers, the members of Altan book aisle seats where possible. So for a fleeting hour or so, while they enjoyed leg-room, I enjoyed the exclusive company of their lead singer. And very charming company it was.
A few hours earlier, the group had played Trafalgar Square, in the climax of the St Patrick's Day celebrations. There were stages at Covent Garden and Leicester Square too, as Red Ken Livingstone gave us the run of the city. But Trafalgar was the main stage and Altan were the lead act. And when they played, unfortunately, I was stuck in an nearby internet café, filing my report of the day's events.
Now, in what was clearly an act of God, I had been granted a personal performance. Not that Mairéad was singing or playing the fiddle on the plane: she didn't have to. The Donegal accent is still music in itself - despite the Morris tribunal - and Mairéad's Gweedore cadences are like a choir of angels. Although our conversation ranged widely, I couldn't remember that much of it afterwards because everything she said just sounded like poetry.
So I was delighted to see this week that she and her colleagues have joined the Dubliners, the Chieftains, and the Clancy Brothers (with Tommy Makem) on a new series of postage stamps devoted to traditional music. This is a considerable compliment.
In the absence of an honours system, featuring on a stamp is the Irish equivalent of a knighthood. And the theme of the latest series is particularly apt for the only country in the world to have a musical instrument as its national symbol.
It used to be that official recognition of this kind was the preserve of people who died for Ireland. In that respect, the new stamps are not that much of a departure. Many's the hard-living musician has fallen in the line of action, and all the line-ups pictured in the series include members who are no longer with us.
While the other groups have been around long enough for natural causes to be a health threat, however, Altan suffered their loss tragically early, when the band's co-founder and Mairéad's first husband, Frankie Kennedy, died aged 38 from bone cancer.
That was in 1994, since when Kennedy's memory has remained a big influence on the band's work, with a winter school named in his honour.
But life carries on and Mairéad eventually remarried: this time the band's accordion player, with whom she has a young daughter.
I remember that because the night on the plane, we were discussing the effects of recent legislation - particularly the smoking ban and the pub curfew for children - on traditional music. Mairéad said that, like many musicians, she had learned by listening to the older people play late into the night in pubs and she worried that this tradition might now be lost.
Pathetically anxious to mirror her concern, I relayed something I'd heard from a fiddle player in Clare: that the smoking ban had wreaked havoc on sessions, especially among younger musicians who had more than music on their minds. A girl would go for a cigarette break, my informant complained. Then the guy who fancied her would be away too. It was very disruptive. Mairéad just laughed and said that for a singer like her, the ban could not have come too soon.
She also mentioned that her toddler was already making shapes with the fiddle. So I confided that my own daughter had just started lessons, albeit in the sort of school where the instrument is known as a "violin".
The classical and traditional methods are notoriously incompatible, I said; and worryingly, my daughter was already correcting me when I used the f-word (fiddle, that is) out of place.
Could she still be saved, I wanted to know? Mairéad though the Suzuki method might help.
Then, before I could inquire further, the pilot announced that we were beginning our descent into Dublin.
All too soon, my date with Mairéad was over.
It was heading for midnight when we disembarked, and sad as I was to part from the band, I didn't envy them when they told me they were driving to Donegal.
It's a tough life being on the road, I thought.
But as I now know, those are the sacrifices you have to make if you're ever going to end up on a stamp.