SIR Alan Ayckbourn's 75th birthday present to himself is a confectionary assortment, otherwise known as his 78th play, Roundelay.

Opening on Thursday at the Stephen Joseph Theatre, Scarborough, it comprises five related short plays, written to be performed in no particular order, as he takes the multiple possibilities of 1973's The Norman Conquests and 1982's Intimate Exchanges.

"They're all quite varied, a bit like a box of chocolates; there’s everything from a dark caramel to a soft coffee cream," says Sir Alan. "The plays have overlapping characters, several of which are in more than one play. The pieces are all related and sometimes elements of plot from one spill over into another."

Some plays are sequels to others, which turn out to be preludes to others. "The fun things about Roundelay are the little reference points from one piece to another. It may be a reference you won’t get if you haven’t seen the other play yet or then again, equally, you’ll know what they’re referring to if you have seen the other play; it all depends," says Sir Alan. "Each play in a sense illuminates the others. I think of them like a circle of mirrors which, depending on the angle you stand, you’ll see different aspects and reflections."

Analysing the appeal of writing a play with such a random structure, Sir Alan says: "I’m intrigued by the thought of how we may perceive an evening which will never be quite the same.

"Indeed, in a sense that is true of all theatre, isn’t it? But in this case it will differ radically and there are 120 different possibilities in which the order of events might happen. As I say, the Roundelay plays have no order and, depending on how you see them, the evening can finish on a dying fall or a comic climax.

"Each play has a beginning and an ending but apart from that they just dovetail into each other."

The random element of Roundelay will works in practice through audience involvement on arrival.

"All the plays are known by a different colour, which definitely ensures they don’t have any order. What I would like is for someone to draw a series of colours – maybe coloured ping-pong balls – randomly out of a hat in the bar before the show," says Sir Alan.

"Then, depending on what’s been picked, we’ll call down to the Green Room to tell the cast and stage management what that particular night’s running order will be. In a sense, the actors will be the last ones to know."

In theory, no show during the run will be exactly the same amid everyone having a slightly different perspective of the same events.

"Indeed. The other appeal, for me at least, is that those who are determined to impose an order on things won’t be able to do so," says Sir Alan.

"In the past, I’ve often been amused when people come up to me having seen, for instance, The Norman Conquests or Intimate Exchanges and say, 'I did enjoy them, though I’m afraid I did see them in the wrong order'.

"Because there’s really no order, you see, they just are. But then a lot of people, when they see randomness, they interpret this as disorder and they have an irresistible urge to tidy things up. In the case of Roundelay, I think there are enough potential choices to make it genuinely random. One hundred and twenty possibilities should ensure there is little chance of repetition."

Among the inspirations for Roundelay was Chris Ware's graphic novel Building Stories.

"You have this graphic novel where you’re invited to just open the box and randomly select a piece of paper," says Sir Alan.

"There’s nobody there to say this is page one. You make your own story by choosing which pieces in the box you want to read next. I liked that idea."

In touching on memory and memories, Roundelay chimes with last summer's Ayckbourn premiere, Arrivals & Departures.

"Memory is interesting to me and it’s a theme which pervades Roundelay. What we remember, how we remember, what we don’t remember. It’s all about memories and what we choose to share and what we don’t choose to share," says Sir Alan.

"What we choose to forget is another point. The rose-coloured spectacles we put on in order to remember something. The romanticism we use to say, ‘Do you remember those good old days?’, which probably weren’t quite so wonderful as we would like to remember. There's an echo not only of Arrivals & Departures but also of some of my older characters, right back to Colin in Absent Friends."

Sir Alan's desire to push his writing in new directions is unabated at 75, resulting in a work where the running order will not be decided until each performance.

"I’m always looking for something that makes an evening just that little bit different without departing entirely from the old basic skills," he says. "You need to keep challenging yourself. I think this show does that for me."

The Stephen Joseph Theatre Company presents Roundelay, written and directed by Alan Ayckbourn, September 4 to October 4. Box office: 01723 370541 or