‘It’s a safe place for widows,’ said a helper at the last Dartington Literary Festival, when I asked her why book festivals were doing so well these days.

Now that’s not much of a slogan. ‘Safe for Widows’ carries all the dank, characteristically British, low expectations of a sign I saw this week outside a lock-keeper’s cottage outside Hertford – ‘Don’t pet the dog; it may bite’.

But the truth of it is that literary festivals are not only safe, but they're also the last places that cater for the hundreds of thousands of erudite, curious, well-read people in Britain that you never come across in the papers.

Contrary to the popular picture of