Bert Coules expressed precisely :
All three bulbs came from a DIY shed multi-pack. Though it seems unlikely,
is it possible that there was something faulty about a whole batch of them?
Failing that, what else could cause this problem?

Numerous places mistakenly sell lamps intended for 230v, whereas what
is needed for the UK is 240v lamps, which means they just don't last
very long.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk