Further to the above I've just come across this on a website:
"The actual voltage tends to be over 230V, whereas in Spain it is usually well under, and can be as low as 206V.
The capacity ("potencia") which is controlled by a trip in your main circuit breaker box. Common potencias are 3.3Kw, 5.5Kw and 8.8Kw."
I'm having my 'potencia' upgraded, what to I don't know yet as I haven't been given the costing figures yet (the standing charge goes up with the increase).