"Merryterry" wrote:
Can anyone suggest the best way of sealing in rust stains from cut
nails that were used to fix the skirting in my 30 year old house?

Cannot remove them without messing up the surface of the skirting. The
nails got slightly damp at some time.

I wish to repaint the skirting but the rust marks always seem to come
back after a while.

Drill down about half a centimetre, apply a rust killer such as Jenolite,
leave to cure, fill with putty, leave to skin over, rub down, then paint
over.