"Phil L" wrote

That's because it's metal, have you tried a different drill bit? - there's
a possibility it could be angle iron, in which case it could be 10mm
thick, maybe you need some adhesive instead?



Yeah, I tried some metal drill bits, but I'm not that optimistic about their
quality. I just ordered a selection of HSS bits, so hopefully they'll do the
biz and zip straight through.

In terms of adhesive. I had thought about it, but what happenes when the
missus decides she doesn't want them up any more? I bet NoMoreNails leaves a
right mess of the plaster when you prise the blinds down in years time? Is
this so? I don't want to be doing plaster repair work after I take them
down.