The early ones are a little different Jim, they use regular 10.9 bolts, they isn't enough space to get a ring spanner on, and not enough clearance to get a socket on there. So its a case of trying to get a good open ended spanner in there.

As you can see after a couple of hours buggering around the thing still wouldn't budge.



At this point I got the angle grinder out and chopped the head off, finding out in the process just how hard a 10.9 bolt is.
I thought I might be able to get some grips on the remaining bolt and twist it out with the tension taken out of the bolt, but in the end I didn't need to, I just unscrewed it with my fingers.
The bolt wasn't seized at all, it had just been done up by a gorilla with an airgun set on Max.