Andy Hall wrote in message
...

Are you sure?

The OSG and Whitfield illustrate and seem to say that a direction
change without an accessory can only happen if the point of
direction change is within one of the corner or top of wall 150mm
bands; not even where a cable goes down vertically from an accessory
to the floor.

BS 7671 itself says: "Where the cable is connected to a point, accessory or
switchgear on the wall or partition, the cable may be installed outside
these zones[*] /only in a straight run/ either horizontally or vertically to
the point accessory or switchgear. [My emphasis]
[*] Meaning the zones within 150 mm of corners or the top of the wall.

That does seem to exclude Dave's interpretation, since that would require
two straight runs. Whether or not this is what the original authors
intended is a moot point. If you regard horizontal and vertical strips
running the full width and height of the wall from every accessory as 'no
go' zones for inserting fixings, then Dave's interpretation introduces no
further risk of damaging a cable.

BTW - to the OP - these requirements were introduced in the 1987 amendment
to the 15th edition and were effective from 12th June '87. Therefore your
house, rewired in '82, may not comply.

--
Andy