Hi Pete !
I sit here with a pair in front of me - drive side right hand thread, gear side left hand thread.
I tend to put the flywheel in a vice (use soft-jaws, bits of scrap ally or even paper if worried about 'bruising' the flywheel) and use a socket with a long extension bar (old Matchless fork legs are good for this!). And getting the nut really really hot beforehand (ie 'sizzling spit' hot) will help.
Putting them back together, again flywhell carefully but firmly in a vice but don't need anything like the same force as the nuts aren't very strong and shear at quite a low torque (about 25 ft lbs from memory, hopefully someone out there can help with the exact figures).
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)