Possibly screwed too tightly, although it looked to be in normal shape, the screws were tough to get into the joist after drilling a 2mm pilot hole, and there is some artex on the ceiling.
In the meantime, I've written to BG Technical dept for their comments.
Mr Green, thank you so much for your swift reply.
Does this mean that the switch does appear to have a "central OFF" position in-between, instead of going back and forth L1 to L2?
Presumably, if it were going back and forth, then bridging the L1/L2 would mean the light being on all the time.
Dear All,
I've just been reading the following post which says that it's no problem to use a 2 way pull cord switch on a 1 way circuit:-
https://www.diynot.com/diy/threads/can-i-use-a-2-way-switch-on-an-1-way-circuit.278152/
I've installed a replacement switch, which was only sold as a 2 way...