“Do you ever forget your lines?” is what people always ask actors. Well, I used to believe I didn’t — until, for the only time, I missed saying the most obvious thing in the world — “These are very joyful tidings”, about the other character’s brother not being dead after all — in the fourth week of “The Importance of Being Earnest”. A play I have known all my life, and have done four times.

One of those times, my son Richard, who is a qualified sound engineer, was in the cast as an ASM, valued for his set-changing muscle as well as his technical expertise, and appeared as footman James — his middle name. When as the prim Canon Chasuble I had to put formidable Lady Bracknell right with a firm “I am a celibate, madam”, I once added in rehearsal “.. despite James the Footman”. Richard is two inches taller and not unlike me in build — a big giveaway about my ‘celibacy’. I shouldn’t have drawn attention to the line. I always felt in performance that I knew what Frances Cuka’s redoubtable Lady B. would have liked to say in return.

But I started about actors’ memories. I can ad lib on stage pretty well — a bit too well, some have thought — and it’s partly because of the memories of some performers I have worked with who have made it necessary. “I didn’t dry”, people always say afterwards, “I somehow just didn’t think it was me [my cue]”. That time in “The Importance”, it was exactly how I felt, so I avoided saying that, and thanked Miss Prism who had teased the line out of me when I didn’t come in with it. I told myself I hadn’t dried for thirty years until then. At least one old theatre friend knows better.

One of my fairly recent worries was not remembering words but remembering a tune. If my thoughts keep running on two particular shows, it is because they are things I have done four times in each case. The other is Dylan Thomas’s “Under Milk Wood”. The last time I was in it, I played Mr Waldo (as well as Captain Cat, whose lines I had envied each previous time). Mr Waldo sings “In Pembroke City”, and each previous Waldo — name drop alert: they included Windsor Davies and Richard Griffiths — had sung it to the same tune. I think it’s printed at the back of the published script. I could reproduce the song right now, to that tune. But for some reason I was allotted a different one. Nightmare. I was really worried about producing the tune expected of me. The song came some time after the interval, and quite frankly I was singing the damn thing internally to myself, right from the beginning of the second half, to fix the tune in my head. I remembered it!

Windsor Davies had no particular ear for a tune, but he used to get Sinatra’s “Love’s Been Good To Me” running in his head. It had been a cast favourite for passing the time on the road en route to Edinburgh, where we were playing at the Festival. Windsor would approach me in the wings before “Milk Wood” and murmur “Hey, Roger. How does that ‘I Have Been a Rover’ go?” Then I would croon, appropriately sotto voce: “I have been a rover, I have walked alone ….” etc.

Four years later, Windsor was famous in the sitcom “It Ain’t Half Hot, Mum”, and was part of a duo from that programme who had a novelty hit with “Whispering Grass”. It went to Number One!

Roger is an actor, and lives with his family in Greater London