Thanks Wildebus ,spot on . Despite our neighbours having good supply and swapping leads rcd would not respond to test and remained upright.Tried different power sockets still no joy. Found a motorhome repair outfit 10 minutes away who agreed to see me straight away. Drove their , hooked up to his supply and all good with rcd responding to test.
Drove back to same aire ,hooked up all good.
Reparavanning , on edge of Pamplona , highly recommended for prompt attention if needed in this area.