I bought one last night after wondering around London, It was the nicest thing ever! I thought I'd try and recreate it today, and I have had success, though its not frothy and I have no whipped cream!
Pour some milk into a pan and heat. Add 1/2 teaspoon of ground ginger and tablespoon of syrup. (I used some syrup from a jar of stem ginger, for extra flavour). Heat until the milk is warm but not boiling, you can make it frothy if you want.
Make a half cup of coffee an add the milk. Top with cream (if you have it) and ground cinnamon. YUMMY!