Fond of the theatre, in 1972, my wife and I decided to try a new experience. We would watch a play "in the round", a concept which, while it might have been standard in Shakespeare's day, had long since fallen from favour.

The play we would see had the, to us, unpromising title of Absurd Person Singular, and was by a dramatist not then the household name he was destined to become.

So - a new play by a young playwright in "foreign" format. My wife and I hardly knew what to expect, and our hopes weren't high when we entered the "in-the-round" auditorium, a compact, you might say cramped, and dusty room at the top of Scarborough's venerable library, reached up an alley alongside a town centre church.

But the evening was a huge success. Hilarious and deeply sad by turns, the play was the perfect blend of light and dark that came to be recognised as the hallmark of Alan Ayckbourn, Britain's most successful playwright of recent times. Performed "in the round" the action had such immediacy that, ever since, performances on a conventional stage have struck my wife and I as stiff and distant. The actors are up there doing their stuff, rather than virtually among us, living out their drama.

This week the theatre that was such a landmark in our theatre-going reaches its golden jubilee. Named after its visionary founder, Stephen Joseph, it graduated years ago from that upper room in the library, where interval drinks were taken in a backroom shared with the actors, who changed behind curtains. With a small but friendly front of house staff, which never seemed to change, the place had a wonderful atmosphere.

A move to Scarborough's former High School brought fears that this precious intimacy would be lost. But it survived, amid improved facilities. Here Ayckbourn continued to premier what often became West End hits. Other new work featured prominently, and this, really, is what chiefly sets the Stephen Joseph Theatre apart from most other provincial theatres, especially in resorts.

The temptation is to play established hits. But, even at the cost of some disappointments, there is a buzz to be had in watching a play no-one has seen before.

The truth is that the Stephen Joseph Theatre is a world class theatre up here on the North Yorkshire coast. Sadly, this isn't always realised. A decade or so ago, when the theatre had moved again, to the gorgeously-restored Odeon cinema, a row erupted over whether public money should be allocated to the theatre or public toilets. As Alan Ayckbourn has said, it is depressing that such a debate should ever arise.

In the Odeon, the theatre has inevitably shed the hugger-mugger feel of its makeshift homes. The special joy now is the combination of new work in an art deco setting of great nostalgia.

With a supporting programme of music, films and talks, story readings for kids, its own junior section, an art gallery, bookshop and popular restaurant, the SJT is a vibrant place. How it will fare when Ayckbourn, its driving force since the 1970s, is no longer involved, is anybody's guess.

Meanwhile, my wife and I have him and his team to thank for many of the most enjoyable evenings of our lives.