well its a pretty strange set up the rear spindle is quite long and going from one side to the other sets up like this:

nut, washer, chain tensioner that is also the rear mech holder, frame, hub n disk, frame, tensioning device, washer, nut.

the whole axle is pushed backwards to keep the chain tight by use of a tensioner and a screw mounted in the frame on either side of the bike.

hope that makes sense. thank you for your advise i will look into getting a cone wrench.