And why is it leaking? Well, ok, stupid question.
After a semi-futile attempt at power washing the engine and undercarriage of my 110 to establish exactly where the leaks are, I do at least know where the big/obvious ones are. It's still filthy under there though! This is a little one, but have no idea what it is. Thought I'd ask before undoing it - it's smack bang in the top middle of the engine in front of the carbs and appears to be leaking gas.
My apologies for not putting a picture inline. Too much bloody trouble.