I've heard the same thing. In the UK the winters aren't very cold and the summers aren't very hot. They say it's because the temp of the sea doesn't change too much and that moderates the temp swings on nearby land. The interior of large continents can have much larger swings.All I can say is that, in the almost forty years I've lived in Maine, there's always been more snow inland. I don't know the science of it, though.
It's all for grabs now though. The temp in the UK is abnormally high for its latitude because of the Gulf Stream which is made up of warm tropical water. The Gulf Stream turns on and off over geological time, if global warming melts the ice on Greenland the flow of fresh water into the ocean would stop the Gulf Stream and the UK would be like northern Canada. We might have to reclaim our territories in the New World.