For a while now, we've had a damp patch on one of our ceilings. Today, I
finally got up into the attic, and found that some of the felt under the
titles has come down. Not a huge bit, probably about 300mm square.

I really don't want to have to re-felt the whole roof (and we can't afford
that at the moment anyway), so I'm looking for ideas on the best way to fix
this from the inside. My "bumper book on DIY" doesn't really say much about
roof felt!

Thanks,
A.