You Are 45% British
You're about as British as a half hearted Anglophile... in other words, a piss poor Brit.
If you are indeed from Britain, you probably consider yourself a European more than anything else.
If you're trying to pass for a Brit, you're going to have to try a little harder.
Go to a football match. Drink until you puke. And head in to work the next morning totally hungover.
---> Quite accurate, as I'm genetically half British but grew up abroad. On the other hand, in the cosmopolitan environment I live in, I frequently find myself being the most British person around. Which says more about the lacking Britishness of the people around me than about me, I suppose ;-)