I have a couple of these emergency fluorescent tubes (about 12 inches
long). Leave plugged into an electric socket and they come on when the
power fails. Last for 2 hours.

I got mine from a friend who is refurbishing some accommodation at an RAF
station. He salvaged a number of them from a skip. They are meant to be
permanently wired into a lighting circuit but work equally well with a
plug attached to them.

I have also seen them for sale at an MOD surplus warehouse, but I can't
remember the price. I live in hope that a couple more freebies may arrive
some day.

Malcolm Webb