On Sat, 22 Aug 2020 17:45:15 +0100, NY wrote:

I can understand the problem of circular calibration, but I'd never have
been able to discover or even guess what it was from the phrase,
assuming I hadn't already heard of it.

Nor me. At first, I assumed it was to do with overpopulation (some may
recognose the reference).



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor