I started keeping a diary in April 1969. It was always intended as a record of the way I spent my days, and nothing more than that. At that time, a month or so short of my 26th birthday, our lives revolved around our first child, Tom, then six month’s old. Keeping the diary was a way of making sure that I wouldn’t forget what his childhood was like. (I would have loved to have had my parents’ account of my own early years.)

I’d just given up smoking, so my will power was on a high and, believe me, you need deep resources of will power to sit down every morning and write about the day before. But it soon became a habit, though there were times when I was working so hard writing a new TV series, called Monty Python’s Flying Circus, that it was increasingly hard to find the time to keep it up.

I persevered, and in 2006, took the decision to start publishing edited extracts from the millions of words I’d accumulated. The main reason was that I was getting frequent requests to write my autobiography. I thought to myself that the diaries are my autobiography, and a daily account of what it was like at the time was likely to be more honest than looking back and smoothing out the rough edges. Weidenfeld and Nicolson contracted me to assemble three volumes. Beginning at the beginning in 1969 and covering ten years each, The Python Years, Halfway to Hollywood and Travelling To Work cover my working life up to the end of the last century. And that’s all. For now.

But 47 years later I still can’t kick the habit of writing a daily diary, so I guess this isn’t quite the end of the story.

Read extracts from The Python Years, Halfway to Hollywood and Travelling to Work.