Now with the dome port polished and decent conditions and no more winter bugs I finally had a good go with this new lens.
Results were very nice, much more contrast and sharpness than the Nikon 18-55 kit lens.
More photos here
This lens is actually a little too fat to fit the Ikelite housing using the spring zoom ring supplied. An easy work around is to add sticky-back velcro to the inside of the gear ring. This provides enough grip to operate the zoom.