Ian, I was at that same show in Newcastle. It may have been the stage premiere, but of course the play/musical was written for TV and had been broadcast by the BBC. Among its many memorable lines was "Lord Shaftsbury dreamt he was making a speech in the House of Lords, and when he woke up, he was."
I was a lifelong Leeds fan, but living in Belfast. A mate of mine travelled up from London and we met in Newcastle, specially for the play. We listened to the match on his car radio in Newcastle city centre - a difficult afternoon for a Leeds fan! Even worse than the result, the Sunderland manager Bob Stokoe later confirmed that the Leeds manager Don Revie had tried to bribe him to guarantee Leeds the win.

Alex was certainly a fine songwriter, and and accomplished performer too. I think he may have had some involvement with a theatrical revue, the Northern Drift, (with which a playwright called Henry Livings was also involved). At one time Alex had a regular TV slot on someone's show (Bernard Braden? David Frost??)