In message , Brian Gaff
writes
Well, many have outriggers, and need a solid bit of ground under those to
stop it tipping over.
Is capping a chimney that much harder than fitting a tv aerial?

Our one was done with two ladders, one the normal sort the other the hook
over roof ladder. I've been given to understand this has been done quite
recently in this street using the same method.

From what the OP said in a followup, this chimney stack is on the end of
a hipped roof. So that sort of access technique can't be used as no
where to hang the roof ladder from.
--
Chris French