Gentlemen, thanks for you help.
I cracked it this morning - it was quite straightforward when I sat with the bits and the wires with my test bed. I confess to a bit of a panic when I first opened the box, but when I used Cliff's diagram and compared it to the switch, the only issue was which terminal was the frog. I was correct in my last guess, only one set of terminals is used for frog switching - the other must be for something else related like a signal.
I got really mixed up and confused with the power supply and of course the power polarity to be switched comes from the rails above and not the power to the solenoid which in my case is a separate supply to the power to the rails.
Really happy now I can get on and start to get the track bedded down and fitting the solenoids. I can't run any trains until all the points are wired as they are all electrofrog.
Thanks once again