Thank for the replies (and speed of replies as well!).
No amount of trying to prise off or loosen in any direction worked. So in the end I just tightened the white plastic as much as I could from what I could get hold of.
Needs to run a full bath to check properly but seems to be sealing...
I'm wondering if anyone can help.
my bath overflow is leaking due to having become loose but i'm having a problem removing the chromed rotary knob that controls the pop up waste. every single instruction video/forum/piece of advice tells me to remove the little retaining screw holding the...