Italian Sausages - London

Since arriving in London 6 months ago, I am unable to find suitable sausages- or Italian ones. I've tried various types of cumberland sausages, making sure they are at least 85% pork. I've tried various flavored ones from my local butcher. I asked him about Italian sausages, and he looked at me like I was nuts. Then he tried to point me to the cured meats.

Does anyone know of a place to purchase Italian Sausages?
Why does the "regular" sausage taste so different from North American sausages? They just don't seem nearly as flavorful.