[eluser]jhob[/eluser]
Right, I have it sorted at last!
I wasn't calling it directly but I was calling it incorrectly. I had wrongly assumed that because I was including ajaxfw.php I should also call ajaxfw.php?item/favourite. When I change it to ajax.php?item/favourite it works.
Many thanks for your help with this. I really appreciate it.
Hopefully that's the last you should hear from me for a bit! :p