In case anyone should chance on this topic in the future when pondering this question, the sheds sell drilling jigs which allow you to stitch-drill the holes around the edges, and diagonally across two corners, for 1- and 2-gang boxes (1 jig does both). They have mounting holes where you first screw them to the wall, and you can then drill rows of holes far straighter and closer together than you could ever hope to achieve by hand.
Once done a few blows with a bolster and club hammer removes the brick, and you're left with a hole so neat that no filling is necessary around the back box.
For a DIYer with only a few holes to sink they are ideal, but for a pro, or for anyone with lots to do they're a bit time consuming.
Can't find a picture of one, but this is the result they achieve:
Once done a few blows with a bolster and club hammer removes the brick, and you're left with a hole so neat that no filling is necessary around the back box.
For a DIYer with only a few holes to sink they are ideal, but for a pro, or for anyone with lots to do they're a bit time consuming.
Can't find a picture of one, but this is the result they achieve: