A phone directory helped me track down Yorkshire Ripper

Imagine a list anyone can access, for free, containing the home phone numbers of everyone in the country, along with their address.

- JONATHAN MARGOLIS

To anyone under 40, it must sound like a privacy nightmare, not least because it involves making a phone call. Having a person's number is like being able to direct dial into their brain at any time, wherever they are - even social media lets you take a break if you put your phone down.

Yet from the 1880s until the end of last month, there was such a list in the form of the telephone directory, or the phone book. Until 2019, when it went online-only, it was a great slab of paper delivered free each year by BT, and before that, by the Post Office.

The printed edition was so massive that London required four volumes, while many big cities had two. As it only listed landlines, however, it became functionally useless around 25 years ago when important calls began to be made on mobile phones.