On Tuesday, 3 September 2019 19:22:11 UTC+1, ARW wrote:

No risk at all IMHO.

Thanks Adam, everyone, will get drilling!

BTW it looks like the plasterers did a good job, a nice continuous seam
of dot and dab at the top of the boards with no gaps.

Yes, although there are some gaps at either end (and down the sides) so not perfect from an air tightness perspective. Better than many I've seen though!