Has the clutch been working OK?
I'm no expert, but looks like its coming from the "end" of the engine so suspect the main crank seal, but thought the clutch would be suffering if it is. Having said that, my son's T Series has a bad leak there and it doesn't affect the clutch. When he had the clutch replaced, the garage rang and said the seal was leaking badly but couldn't source a replacement. We got one from (IIRC) Rimmers which they fitted, but the leak is worse than ever. New clutch is working well though.