Thanks for the replies, I appreciate the depth of explanation C-Stain, that puts quite a different complexion on the matter and raises the issues of lack of understanding of injuries and the consequences of moving people unsupported.
You mention Wilderness first aid (not something we have here) but I imagine is similar to the offshore yachting first aid training we have (years in the coastguard, so everything in my toolbox is marine based). I will have a look at that, as your standard first aid is really stop em bleeding, keep em breathing and yell for help. Not much use when help isn't coming.
Good stuff to learn from, some of the places we ride are remote and I wouldn't have liked to deal with your injury with only the skills I have at present.
Orange...cause it makes me look like I know what I'm doing!