Europe's largest newt, with an average length of seven inches, is the Great Crested Newt (which is also sometimes known as the Northern Crested Newt, although they're mostly found in the centre of the continent - clear as mud.)

Unfortunately, it's an endangered species - there is legislation in place to protect them which prohibits you from killing, injuring, capturing or disturbing them - which I'm sure you weren't planning on doing anyway. Right?