Hi, thanks that's reassuring - 6 inch capping board - do you mean the wide panel near the hinges - that's wood and has always been there. They removed it to fit the door and ended up sticking it back so it's wonky and sticks out more one side now...
Yeah that's the one, don't know why they didn't centralize the door if that's the case then, though the walls could be a different depth as I suggested earlier. Ask a local fitter then is probably your best bet I'm afraid, I'm about a hundred and fifty miles from you.
Not according to the pictures. You can see a 40mm gap all the way through. 6" board needs removing, and that gap needs to be solid (wider frame and door or frame add-on). Do not accept what you have as 'standard practice'. It isn't.