We're in the middle of the fourth verse when I forget the words.
I didn't think this happened when you'd actually written the words, but a live gig is different from sitting on the sofa with your guitar across your knees and only the dog to laugh at you.
"It's OK," I tell the crowd. "This happened to Coldplay at Glastonbury. We can just start again."
And this is what we do because Allan (lead guitar) and Gordon (keyboards) are experienced musicians. Only one of us is incompetent.
Luckily, I'm better on the hip/hop/trance number, mainly because I can hide behind a phoney West Indian accent while wearing a baseball cap back to front. I smile apologetically at Owain Glyndwr.
Owain doesn't smile back. He looks kind of furtive. In this ancient painting he's in disguise, too, wearing the friar's habit of local hero Sion Cent. It's far from an official portrait but I'm convinced it really is Owain, because we're at Kentchurch Court, the stronghold of the Scudamores, on the Monmouthshire border. Owain's daughter, Alice married a Scudamore, and this is where he's widely believed to have retired (and then vanished) after his final defeat. And the face in the picture is eerily similar to the great man's living descendent, John Scudamore.
The family have been at Kentchurch for over a thousand years, and keeping a place like this intact gets harder all the time. Which is why, for a reasonable fee, they're letting us use it to launch my new novel.
Yes, I realise it's only a few weeks since I was mocking the writer Jasper Fforde for promoting his work at fan-gatherings like The Fforde Fiesta. Well, I'm sorry, that was part of the cover-up. My launch for The Secrets of Pain, is even more bonkers. But it's the sort of thing writers are having to do to stay afloat in the Internet era, in the same way that illegal downloads are forcing rock bands back on the road.
The band. I'd better explain. The new book is part of a series, and one of the regular characters is a singer and songwriter. Snatches of his lyrics, ghosted by me, have appeared in the books. One day, Allan Watson, a long-time reader and composer up in Glasgow, emailed with an offer to write some music and actually complete the songs.
It was an intriguing idea, and within a few months we had an album. Eighteen months later we had two, and on the second one I actually did a bit of singing. So now I'm in a band, and we're playing live to about 150 readers in Owain Glyndwr's retirement home.
Performing at Kentchurch Court
Suddenly, with ebooks and audiobooks and literary festivals as common as rock festivals, publishing a novel has become a multi-media phenomenon.
The original idea was to hold the concert outside - a real Glastonbury job, with a backcloth of the border hills and the deer park. It's well-known that Owain Glyndwr was good at managing the weather, and I was hoping he'd shift a few clouds for us. But half an hour ago it started to rain and we had to carry the amps back into the house.
Inside, there isn't really enough room or sufficient seating and one bloke walks out because he can't hear. But, with a stained glass window behind us and the chandelier overhead, the atmosphere's amazing.
And, of course, there's someone else to make up the numbers and he's wearing a friar's habit and he can see every chord I fluff.
Owain's very strange unofficial portrait is actually hanging in the area of Kentchurch we're using as a stage - me and Allan and Gordon, down from Glasgow for the day, and Krys on backing vocals and Terry, the blind painter, on second guitar. We fixed up for Allan to spend the night in the dim, oak-panelled, four-postered room known as Glyndwr's Bedchamber where, in spite of me repeatedly assuring him that it was seriously-haunted and he could expect to lie there shivering until dawn, he seems to have slept very well.
I'm still nervous, though, and keep glancing at the face in the picture. However, apart from the afforementioned forgetting of lyrics, nothing strange happens. Not on stage anyway.
But, at the end of the passage, is the Ladies loo...
The women's lavatories at Kentchurch are very ornate and contain a grandfather clock. I know this because afterwards I get a guided tour from Jan Scudamore, who runs things.
Yes, earlier, a friend from Aberystwyth emerged from this same convenience more than little shaken. Seems she was on her own in there and, on the way out, her shoulder was gripped - quite hard. By an unseen hand.
If I was making this up, I'd go back up the stairs to the wall beside the big window and the face of the man in the friar's habit would have acquired a small, subtle smile.
In fact, I don't like to go back up there, so we'll never know.