It is panelled, probably thin ply, and now painted so repairs can be hidden.
However, around the hole c. 3cm, which does go right through, it is all hollow inside which rules filler out.
I bought some expensive knobs before undoing the old handles when I found a large hole (for the bolt bar) underneath. While the door knob rose covers the hole, the screws on the top do not catch any wood.
Any ideas for solving this problem?
My bathroom fitters have left me with half a dozen badly cut ceramic bottom row wall tiles that do not reach the sub-floor. In places the gap is 1cm wide! I have Amtico tiles, which obviously will not hide the gaps, ready for laying down and would appreciate any ideas for neatly hiding the gaps.