*Feels so embarrsed*

Yep Gambit was right, figured this out earlier when I took a better look, been raining hard down here lately.
It just a clip round the water pipe, it's rusty/browny water that was dripping, not oil i don't think! Must have got disturbed when the head came off!
The clip is the one that you need four pairs of hands and three mole grips to get off! can I just replace this with a jubilee clip?