What a waste of space this was. My customer is in a new house and knew that there was an empty void under the stairs so asked me if I could make a cupboard.
We didn’t disturb the skirting to maintain the clean lines and we made a framework to which we could attach the door that was made onsite from 12mm MDF with a 12mm screwed and glued framework to the rear to keep it rigid.
The customer wanted to paint it so I left it with all the screw holes filled and ready for sanding. My compliments to the customer on a great paint finish!