[Symbiote]

They were probably too expensive, or not sufficiently reliable.

> With the spread of electricity and affordable alarm clocks, however, knocking up had died out in most places by the 1940s and 1950s.

> Yet it still continued in some pockets of industrial England until the early 1970s, immortalised in songs by the likes of folk singer-song writer Mike Canavan.

The reason for that isn't clear.