SMEG UKPARMA tap is dripping - how to get into it?

I've got a SMEG UKPARMA tap which has started dripping from the control lever.
http://www.appliancesdirect.co.uk/p/ukparma/smeg-ukparma-tap
There's a single screw near the top of the base which I think holds the water spout in place but allows it to rotate. Nothing else visible.

Any idea how to get to the insides to fix the leak?