Adrian, I'm gonna go out on a limb and assume that pike flies that work elsewhere would be successful in our neck of the woods. Some of the more successful patterns are crossovers from saltwater: red and white seaducers, decievers, whistlers, etc. And then there's the Dahlberg series of flies, which are his diver series (rabbit strip diver, mega diver, diving bug). Some of these patterns are 6 to 7" long, tied on 3/0 hooks. And yes, frog and mouse patterns can be quite successful at the right time.
It seems that successful pike flies don't have to necessarily imitate anything specific in nature. Rather, they play upon the pike's predatory instincts by appearing to be weak and reacting to the predator's prescence. A vulnerable and easy meal.....usually something bright and flashy that stands out.
It's almost as much fun to talk about as it is to do.