Changing valves in a Brixton quest kitchen tap

[Reddwarf4ever]

Have removed the cold valve easy enough, but the hot valve will not unscrew, have used a spanner and mole grips, but both start sliding and starting to damage the nut surface, is it possible that the hot tap valve unscrews the opposite way ? I assumed both would be anti clockwise to unscrew, also wonder what size the nut is to get a socket or ring spanner to help.

Many thanks

P.S. never seen so many adverts on a forum before, so difficult to read posts on a tablet