On Apr 6, 2:38*pm, (Windmill)
wrote:
From the street I can see a few cases where a TV mast has been strapped
to a chimney (the approved method AIUI) but, despite the metal corner
brackets between the strap cable and the chimney, the render has been
cracked at the chimney corners and has separated from the underlying
brick.

Is there any way to make this less likely, given that a cable would
probably need to be under a fair amount of tension to hold a satellite
dish firmly in place?

I think you'll find the cracking is due to the mast waggling in wind.
Esp. if it's a tall one.
The bracket is attached too high, there is insufficient weight of
brickwork above it to resist the tension forces generated.

A dish would be worse as it catches the wind.
Many chimneys are in bad state anyway, esp on older houses.

So, down to cowboy aerial fixers.