The missing face was a disconcerting part of having my portrait painted for the National Gallery of Ireland, writes Maeve Binchy, after its unveiling last night.

When the National Gallery of Ireland first suggested it, I had the very real fear that it might be some terrible practical joke. That it could be a Candid Camera style television programme watching people making fools of themselves by accepting huge honours like that and then having to bluster their way out of it.

But they seemed serious. So I was utterly delighted and waited for the artist to arrive.

She was Maeve McCarthy and had been at the same school as I had, though admittedly a quarter of a century later. We talked animatedly about loved figures and less-than-loved figures in the place, and had a great bond.

I had looked her up and seen how successful she was, as well as all the competitions she had won. She had painted a self-portrait which everyone had said was very good, but in real life she was good-looking, and the self-portrait had made her look a lot less attractive than she was. If she's so tough on herself, I thought, what is she going to do to a subject? And I sort of hinted that.

But she explained that there were various conventions about a self-portrait, which I thought was all very well in theory but going to be a bit tough on me if she was into too much gritty realism. Still, we were into it now.

She told me the bad news was that she couldn't paint from photographs, but the good news was that I didn't have to sit still. I could move about and talk and drink mugs of tea and everything.

So I was busy then trying to look for nice bits of our house to be painted in - near the one good piece of furniture maybe, with some tasteful glass arranged on it?

She said she would like to prowl about the place looking for a setting and could I just get on with my life so that she could observe me?

So I chose a day when Gordon (my husband Gordon Snell) would be out and I got on with life, trying to ignore her. For a whole morning I yacked away on the phone, typed with my four-finger typing, looked things up in the dictionary, stroked the cat who had settled in the Action This Day basket, and had a script conference about a project with Jean Pasley where McCarthy was most helpful and came up with some good ideas.

After a day of prowling she had chosen the location. It was to be upstairs in our study where you can see Dalkey castle in the background over the roof. And she wanted Gordon to sit in on the roof terrace - sort of out of sight but with his legs in the picture. His legs? Yes, just his presence around the place apparently, and he would be reading The Irish Times. What? Product placement? No, you would only get a hint that it was The Irish Times. Right. Right.

So we had the first sitting; there was some discussion about the colour I would wear, and eventually I settled on blue. Maeve McCarthy set up her easel and I sat down nervously and waited for it to begin.

We talked about everything under the sun - life, death, hopes, disappointments, friends, family, travel. And then the sitting was over.

I had heard you must not look at your own portrait until it is finished. But she shrugged. Of course I could look at it, she said.

Interestingly, there was no face.

Lots of Dalkey castle, and the roof, and the desk I was sitting at, and big blue shoulders, but no face.

I managed to say nothing. After the fourth sitting, when there was still no face - only pixelation like they put in a newspaper to hide the face of the Accused or the Suspect - I thought I would mention it.

"Oh I won't do your face," she said, at which I felt dizzy and wondered had I entirely misunderstood the whole thing.

"Not until much later," she added to my relief, and the blood returned slowly to my veins.

After the sixth sitting, still no face as such. She asked me if I liked the picture. We were such friends now, I had to be honest. "I spend over €20 each time you come getting my hair done and it doesn't really show. I wonder does the hair look a bit flattened in the portrait?" I said nervously.

"You're very lucky you didn't have Gwen John painting you - she made subjects put Vaseline all over their heads so that she could see the shape of the skull," Maeve McCarthy said unsympathetically.

And then the pixelation went and I saw my face, and the lovely picture of our cats, and a picture of our friends on the wall, and a mug of tea with Nighthawks on it. And best of all the reassuring presence of Gordon outside the window, reading a paper, which could be The Irish Times. And then it was all over.

Maeve McCarthy packed up her easel and her brushes and her little jars of whatever it was and left.

And I missed her like mad.

She made it all very painless, she was great company and I am as pleased as anything that it was done.

It is a huge honour to be chosen by the national gallery of your own land to hang in its halls, and to be lent a talented portrait painter for a summer of friendship and insights.

I will of course be hovering a lot about the gallery for some time pretending I have come to see something else, or that I am taking some overseas visitors for a tour. But really I will be there to make sure they don't take it down.

The film Tara Road, based on Maeve Binchy's novel of the same name, is on general release