Did not clock all four photos at first!
The extra pair would very doubtfully be going to the loft unless the outlet had always been in the current position.
Looks like a simple fix. The two masters are linked in parallel and the third set will probably be the secondary mentioned on the other side of the garage wall. The cables appear to be surface mounted, so making one an NTE 5 point and linking the other two as three wire secondaries would be simple enough and should solve the problem.
Edit: That is if you need the ring wire.
Knowing how it works is completely different to understanding how it works.
Edited by mrnelster (Mon 11-Apr-11 19:20:48)