wrote:

OK. I think this provides a good excuse to get a ladder stabiliser.
I was
thinking for getting a stabiliser which spreads the load at the top (and
provides a convenient tray) plus one which has telescoping legs to spread
the ground area. Sound reasonable?

I bought one of these standoffs quite recently, for a similar job:

http://tinyurl.com/4pm6g or
http://www.screwfix.com/app/sfd/cat/...72002&id=32096

It really is the mutt's nuts - I now wouldn't even consider doing any
sort of brickwork from a ladder without one now (which isn't to say a
tower wouldn't be better still). Otherwise where do you put the mortar,
the spare brick or bits thereof, the various tools etc, all without
falling off or dropping things. The wide separation of the feet against
the wall really helps make it more stable too.

David