Mark

I've been here recently, there isn't a lot of room to get your hands to the
bottom connector because the p/s pump and alternator are in the way. One
method is, as you say, remove the bumper, but I managed to get my thin
variable jaw width plumbers pliers over both connectors and gently nip them
up. (This is what I mean:
http://www.screwfix.com/app/sfd/cat/pro.jsp?id=99954&ts=58495 )

Once you've done that you can rotate the lock ring with one hand and the job
should be complete. Make sure you replace the O ring while you're in there
too.

Chris