Thanks Bruce, much appreciated. I've done an oil change today, nothing unexpected there.
With the clutch in its pretty much silent, but when you pull away or feather the clutch at low speeds it make a lot of noise, almost a rythmic knock (like big end knock) but once past walking pace with the clutch out it disappears. Its fine under load in the higher gears so i don't think its crank related.
I'm not bothered even if it needs a rebuild as I got the bike at a very good price, I just like things to be right.