Thanks everyone for the help.

Howrdcano, I will see who I can find on Monday to give me a hand testing the servo and driver. Someone else recommended I get an auto electician to test the driver for me too, so I'll try that when the weekend is over. It seems to me that the servo is working fine, but the driver isn't doing anything except passing power from the battery. But I could be very wrong...

Dave, yes - I paid extra to get a continuous rotation servo, and it is working as it should in that regard. It just can't be controlled at all, except for the little servo knob (sorry, don't know the correct term) that changes the direction.

On the piece of paper that came with the driver it has two subheadings. One is "Operation". The other is "speed control operation" and says this: "Simply plug a speed controller into the servo Driver to operate your electric motor. HOWEVER, if your speed controller has a BEC (Battery Eliminator Circuit, DO NOT plug your 4.8 volt battery into the servo driver. This will allow the speed controller to power the servo driver".

I'm sorry to say that I have no idea what the above means? Does it mean I need an extra piece of kit to make the servo driver control the servo speed? It was not mentioned by the guy who made this set-up first...

Rebecca.