I get on well with my sister. We speak most days, although I’ve noticed a certain froideur recently. It took me a while to work out what was wrong. The issue, I realised, was my penchant for offending against one of the most bizarre of all middle-class shibboleths. I’ve committed just such an offence twice in the past few days. I’ve walked out of two plays because I hated one and was bored by the other. (I left at the first interval, I should point out; I’m not so uncouth as to leave while it’s going on.)

It did take me a while to realise I could leave these things early, and the middle class guilt that made me stay was pointless

It seems to me entirely obvious that if I’m not enjoying something I’ve paid for then I should want to leave. Why persist with something that is meant to be entertaining or enriching when you’re finding it neither? When I’m not enjoying a book, I stop reading it. When I’m not enjoying a TV programme, I turn it off.

But I realised long ago that my walking out of a live event horrifies some people. It’s as if the theatre, or a concert or opera is some sort of penance and has to be seen in full. To leave early is a sign of a weak character or moral turpitude.

What rot! I go to concerts or the theatre for pleasure, and if they’re not giving that, cheerio. Last week I left the newly opened Alan Ayckbourn revival at the Old Vic, How the Other Half Loves. It’s had rave reviews but I loathed it. It was like a bad 1970s ITV sitcom with a series of cartoon-like caricatures. I’d booked because it starred Roger Allam, who I have always said I would happily pay to see reading the alphabet. It turns out I would rather have seen him do that than star in an Alan Ayckbourn revival.

Then a few days later it was time to leave The Oresteia as The Bridge. It was updated; I’ve no issue with that in theory, but all this particular updating did was turn a monumental Greek trilogy into a rather dull series of domestic arguments involving a group of uninvolving characters (and one actress with an accent I found like listening to chalk being scraped down a blackboard).

It did take me a while to realise I could leave these things early, and the middle class guilt that made me stay was pointless. I can date it to the performance – a Handel opera at the Royal Opera conducted to death by Julius Rudel. I adore Handel operas but, by God, they can be interminable if the conductor doesn’t get Handel. Here’s the thing, though: they never need to be interminable because YOU CAN LEAVE.

Philip Larkin said that when he realised one could actually walk out of a theatre it was ‘one of the great moments of my life’: ‘I was watching Playboy of the Western World and when the bell rang at the interval I asked myself: ‘Am I enjoying myself? No, I’ve never watched such stupid balls.’ So I just had another drink and walked out into the evening sunshine.’

He’s right. Mind you, I have been known to leave because something is too good.

That was my response to a stunning performance of the Schumann piano concerto by Martha Argerich. The orchestra was decidedly ropey, and the second half was Shostakovich’s Tenth Symphony. Did I really want to hear a masterpiece hacked around by the orchestra? I would much rather have the Schumann as the last thing I heard that evening. So I left at the interval.

Meanwhile, I know the response this column will get, but my mantra is simple: Life’s Too Short. If it’s no good, leave.