Like I've told several people I left my question about the whole IP address thing open and this afternoon I had a reply:
Your internet service provider is routing you through a proxy, which uses
the IP address you saw listed on the error page, but, as you noted, that is
not your actual IP address.
Community Care Team
Now I took this to mean that the server 184.108.40.206 is masking all of our IP addresses and giving it's own. So I rang Sky to find out why. Problem is, they say they don't do this. I asked if they could check the server to see if it is acting as a proxy when it shouldn't be, but clearly that was out of my service chap's remit because he just kept suggesting I reboot my router and see if that changed anything and that the problem has to be at LJ's end.
I tested it out on Dreamwidth and they record my proper IP, however, on a traceroute they don't seem to go through the same server, and neither do any of the other sites where I can see my IP address. So now I'm out of empirical data.
b) that particular server is incorrectly configured and is acting as a proxy
c) LJ blocked a server IP by accident (but then I don't understand why this is registering as my IP when I post anonymously)
d) something else is happening that I simply do not understand
I is still confuzzled.