you mean driver side U.K. (=passenger side U.S.), so that should be the connection for the aux fan at the radiator?
Have you tested the aux fan? Just pull the connection at the rad and bridge the connections, 1 is for low speed and one for high speed.
But the aux fan is usually not required when you go higher speeds, even not the visco clutch. And I can imagine in the U.K. it is not very hot now.