Nice one! I did indeed mean a <500>mm square door. Any smaller and the meter man would have even more difficulty.
Thanks for your reply. It was more the wall itself I was worried about (moving sideways because of the unsupported slope above the doorway)
Paul
Here is a picture (I hope) of the area previously referred to. The red line shows the approx line of the (wooden) stairs on the other side of the (single thickness) brick wall. I want to add a triangular enlargement to the doorway almost up to the red line.
As you can see from the 300mm...
I have a door to the cupboard under the stairs which is only about 50mm square. I would like to enlarge this by making a triangular space above it up to the level of the stairs.
The wall involved is of single brick running from floor to loft (enclosing stairs). It is not a load-bearing wall...