Having a quick look under the bonnet/car when back in glasgow looked like it was the oil feed to the turbo. Not the first time this has leaked on my car! (see here)
Removing the pipe i found that it leaked very slightly when filled with a light oil from the collar joining th fixing to the pipe itself at the non turbo end. I don't know if its something about my driving style, or perhaps my car but i'm fed up fiddling these rigid pipes in and out.
Off to Pirtek i went, £39 later (a little steep i know but i went for the stainless braided option: belt and braces
) they made me up a pipe for the next day, and it looks lovely. 
Its now installed and i've been for a thorough test run up to more than average opperating temperatures
and not a hint of a leak. because its flexy i also chose to install it a more visible/easier routing than the rigid pipe has. Just going to keep an eye on it for the next few miles but overall i'm well chuffed.
the prevously leaky end!
