Thanks for your comment Iswing, yeah I did wonder if there were some other issues. There is a bit of play I think somewhere along the transmission line, could be propshaft, or final drive or maybe in the gearbox, I couldn't tell as am not a mechanic but just mechanically minded! But sometimes on slowing down and then speeding up again, there's a thud, where it kicks in again.
Will have to get it seen to soon.