Antony Gelberg wrote:
A quick poke with a screwdriver indicates a mere 2" before I hit
concrete, so looks like all bets are off. I don't want a false
ceiling
as the current one is only about 7'6" high. Looks like I'm shopping
for
some normal light fittings, but even this could be difficult as I
want
them to be relatively shallow and I haven't seen much that I like.

Probably a blessing in disguise, going by some of the comments.

Antony

There are plenty of shallow lights on the market at the moment - the
ones that look like spots but they're not or the flush mounted dome
type.