“I like to frighten myself as a writer,” Alan Ayckbourn said, “and I called my casting director and told him that the central character for this play, who is on stage the whole time, is a nine-year-old Afro-Caribbean child. ‘Thank you,’ he said, ‘thanks for nothing!’.”

So was born the production process for Ayckbourn’s 73rd full-length play, which premiered last autumn and comes, with its original cast, to the Oxford Playhouse next week. The title belies the content: this is definitely one of his dramas for adults, dealing with sexual politics and pregnancy — leavened with a touch of assault — but all sieved through the eyes of young Winnie, who has to write a composition for homework called “My Wonderful Day”.

I asked Ayckbourn if it was important for him that the play’s two central roles are played by black actors — one of apparently a very young age.

“The nine-year-old was more significant than the black. But we did realise early on that if we were going to have a genuine child, we should have to use at least two of them, and then you’d get into that awful business of one being slightly better than the other. So the actor playing Winnie (Ayesha Antoine) is, in fact, 28, although audience members have put her at 14 or 15. She weaves her magic.”

As with almost all his previous plays, Alan Ayckbourn directs this one — he’s also directed the West End premieres of them all since 1977. I asked if it was an essential part of his creative process that he also directs?

“The two careers started together. Stephen Joseph, my mentor back in the late 50s and early 60s did his best to get me off the stage as an actor and get me into the auditorium either as a director or writer.

“Initially, it was not considered the done thing — pace Noel Coward — to direct your own work. But most of my later work, including My Wonderful Day, has been written by me as a director-writer: a lot of that play is not on the page and we worked on it rather filmically.”

His 50-year working life in drama may have appeared to have moved calmly along a successful path after 1959’s The Square Cat, through the hugely successful runs in the late 1960s of Relatively Speaking, How The Other Half Loves, Absurd Person Singular and The Norman Conquests to his present ‘Grand Old Man’ status; but there was a vital moment in 1963 when everything looked as if it might go terribly wrong.

Ayckbourn had written a play called Mr Whatnot, garnering terrible reviews.

“That was a sort of St Valentine’s Day Massacre,” he told me: “I mean, everyone had their machine guns out, and quite rightly as it turned out!

“That was the case of a play growing out of a small regional concept and being presented vastly overblown in a West End context.

“It was like a grossly-overdressed Christmas tree that fell over.”

He retreated to BBC Leeds as a radio drama producer to lick his wounds, but crucially kept writing.

“I went back to the drawing board. A few weeks after that debacle, I had vowed never to write another play; but dear Stephen Joseph came and told me to have another go and try to write ‘a well made play’. And I was at an age then when I thought I was cutting-edge — a great young experimental dramatist. But I sat down and over a few nights wrote Relatively Speaking.”

The rest, as they say… Ayckbourn, as artistic director of the Stephen Joseph Theatre in Scarborough from 1972 until last year, had the perfect toy to play with and a practical reason for his vast output of drama: a space of which he was in charge, and a space that needed filling (“my own personal place to experiment and fail”).

He might have stayed on running the theatre had it not been for a stroke in 2007, but he, unsurprisingly, remains extremely busy.

Is there, I asked, a 74th play ready and waiting?

“Yes, I’ve got another one and it’s actually got scheduled rehearsal dates in July this year in Scarborough and before that I’m doing a revival of a much older play, Taking Steps, in Richmond.”

Stupid question, really.