Originally Posted by AJ.
Well thanks all for the responses. I think that is fairly unanimous although I could do with a few more responses just to be absolutely sure
So which bit am I angle grinding, is it that little rod thing on the last pic?
Seems to me that the locking bit is the right end of the rod in the third pic. Unlocking the thing allows the pin to slide to the left, clearing the wall of the cylinder, after which you remove the lock towards the camera. If that's true, cutting the rod won't get you anywhere, as the stub will still be stuck in the lock part.
You'll need to cut the cylinder part beyond where the pin goes in (or at least halfway along the pin diameter) such that the pin is no longer holding everything in. Remove the lock and you should have access to the nut or bolt head.