In reply to Tall Clare: Thanks Clare, I had read that already - it surprised me that it was that far down the list of FAQs. It appears that the Zque accreditation scheme bans mulesing - but doesn't mention anything about slaughter policy.
A bit of internet searching just now turned up the PETA website which suggests that mulesing is still widespread, with the Australian Wool Industry getting most criticism.
Looking at
http://www.savethesheep.com/animals.asp - this suggests that a large numner of Australian and NZ sheep are shipped in overcrowded conditions to the Middle East for slaughter - often having their throats slit while fully conscious.
I think need to look into this more, but for now I'm happy to continue with my synthetic Hellys and Polypros.