It's... Monty Python's flying opera house

Anne Dudley, the Oscar-winning film and TV composer, rang up to say she'd just been commissioned by the Royal Opera House to write a short opera for ROH2, and would I be interested in writing the libretto?

I'd met Anne through Steven Isserlis, the cellist, also famous as my youngest daughter's godfather. I'd played Steven some music I'd commissioned for a song I'd written, and he didn't like it at all. He said he'd introduce me to "a real composer". I jumped at the chance, and it turned out to be Anne.

My partner, Anna Soderstrom, and I had already written a libretto for a – sort of – opera for the Sao Luis Teatro Municipal in Lisbon, Portugal. The composer Luis Tinoco had set some of my children's stories from Fairy Tales and Fantastic Stories to music the year before, and the theatre suggested another collaboration. That turned into Evil Machines – based on another collection of stories I'd written.

We wrote the libretto for a telephone, gas cooker, alarm clock, washing machine, two parking meters, a motor bike, six wild cars, a petrol pump, a remote control and a 15-ft giant Hoover. I thought as I was writing it: "I have no idea how they're going to do this, but that's their problem."

The theatre then asked me if I'd like to direct it. Of course, I couldn't resist, and so their problem became my problem, and we spent two wonderful months in Lisbon getting the thing on the stage.

The new opera with Anne Dudley was going to be a proper opera. It was commissioned for the OperaShots slot at the Linbury Theatre, the ROH's studio theatre. OperaShots is a double bill of new short operas with the focus being on established artists in their own fields experimenting with this art form. Stewart Copeland will also be bringing Edgar Allan Poe's Gothic fiction The Tell-Tale Heart to life. Commissioned and produced by ROH2, it is part of an ongoing programme of opera development work across the Royal Opera House, which ranges from full-scale commissions to development workshops, courses and observer programmes. I was told it should be about half an hour long and could be about anything. But what?

My partner, Anna, suggested I base it on one of the stories in my new collection of children's stories, Animal Tales (to be published in April).

The story is about a wonderful doctor, whose patients all love him and who has a wonderful cure rate, but the General Medical Council say he's got to stop practising because he's a dog. The patients complain that it doesn't matter that he's a dog because he's such a wonderful doctor. But the GMC say it isn't hygienic to keep a dog in the surgery.

I put the idea to Anne and she was a bit doubtful at first. So I wrote out the opening scene, so she could see the sort of thing I had in mind. I'm pleased to say that she thought it was something she could work with.

We then went to the Royal Opera House and pitched the idea to Alison Duthie, Head of ROH2, and John Lloyd Davies, Head of Opera Development. To our surprise, they didn't seem to be the least phased by the subject. In fact they were positively enthusiastic about it. Anne and I left in a cloud of euphoria. And it got better.

Writing the libretto was a joy. I can't remember how long it took but it seemed to write itself. I'd taken the idea of the story as the basis but carried it on further, without any idea of where it would go. But as I wrote, everything just seemed to suggest what should happen next, and I was never stuck. When I handed the libretto over to Anne I was careful not to whistle any of the tunes I'd had in my head as I was writing. But I did record a reading so she could check if ever she had any problem with the stress of the words. I think there was one place where she found the recording useful but I was never quite sure.

Anne rang me to say that she'd set the first half to music and did I want to go and listen? Did I ever? I sat for an hour listening to Anne singing and playing the score. I thought it sounded like real opera and not at all like the musical comedy I'd had in my head. That meant that it was classy. A fact I can confirm, since the more I listen to the music, the more I love it.

But one fact became clear after that first try-out: it was not going to be half an hour. It was going to be an hour. We thought this might be a problem, but the ROH were very accommodating, and didn't seem at all worried by the fact that we'd exceeded our target time by 100 per cent.

Directing it has also been fun – so far at least. Last year, the ROH suggested we might like to try it out with professional singers. Anne and I jumped at the chance. That's one of the wonderful things about working within a structure, like the Royal Opera House: they've done it all before.

They supplied us with a short list for the cast, which cut down the number of casting sessions we had to have. They've supplied a brilliant designer and technical staff. Which all takes a load off my shoulders. As director, I don't need to worry about any logistical stuff, or ask myself "what should we be doing now?" I can concentrate on what is going to go on stage.

April 8 is our first night. Nerves? Not yet. But watch this space.

'OperaShots' – world premieres of innovative opera by Anne Dudley and Terry Jones / Stewart Copeland 8-16 April at 7.45pm, Linbury Studio Theatre, Royal Opera House (020 7304 4000; www.roh.org.uk)