When we are not doing something infinitely cooler with yeast, home- made photographic paper or Nintendo controllers, the people I work with sometimes run workshops on making short video films. If I'm at the helm, I flag up the use of the undo button in effecting recovery from disaster caused by a careless click or drag.
"I heard someone once say they wished life had an undo button," I often remark, attempting to inject a wistful tone to disguise the fact that this is a fabrication. I can't recall ever hearing anyone say they wished life had an undo button, though superficially the idea has appeal. I'm sure I would have clicked it many times, usually just after speaking. However, I have seen enough science fiction films to know that a tiny change in the past can cause a huge change in the future.
Zap back to October 1985. I am in my third year of teaching. My friend Brian is home from university for the weekend. He has arranged a night in a local pub and has asked a girl called Kathleen to come along. He went out with her for about a microsecond in first-year uni but has kept in touch. She's a music teacher, so we will have something to talk about. I walk into the bar, and suddenly all the indicator lamps inside my head that say "somebody you need to get to know better" light up like the control panel of a jet.
Kathleen tells of borrowing a cassette tape from a colleague she doesn't know very well. Her tape deck has eaten it. She can't find a replacement. Next day I am on a mission. I go to absolutely every record shop in the centre of Glasgow, looking for this tape. Not finding it, I expand my search area to take in the bootleg hell of the Barras, where stalls sell everything from the (allegedly) knocked-off mainstream to such delights as "We Hate the IRA". Nae luck.
Plan B. I write to Kathleen at her school, asking her if she is sure she got the album title right. Two-and-a-half years later, we get married.
What has that got to do with life's undo button? I dare say I might have tried to undo crashing my Triumph Spitfire a year or two before meeting my wife-to-be.
However, maybe if I still had it, it would have let me down that night. Perhaps, to save the embarrassment of telling its owner she had mangled it, Kathleen would have undone borrowing the cassette tape that gave me an excuse to get back in touch (though I would have found a plan B).
When I begin to think of the delicate, random mix of genes that made my children who they are, I conclude that I daren't change anything, ever. Every skinned knee, fall from a motor bike, dodgy take-away, every moment when my heart rate shot up and my face turned beetroot in an unruly class.
Yes, all those times when I was the man who put the "tit" in practitioner will just have to stay. I simply can't risk a careless ctrl+Z putting somebody different in the home movies.
Gregor Steele might have undone buying a Vauxhall Cavalier in the early nineties, given the chance.