Thanks for the replies guys :)
It's a manual, no coolent loss or obvious source of leaks that I can spot. I wondered about the air con, this usually dries on the drive and leaves no mark - what drew my attention to this was that the spots were leaving their mark. However, air con was on pretty much throughout the 400 mile drive yesterday... a spot or two dripped from the same spot this morning after a quick run - without the air con on. I'll leave it off for the next day or two and see if it continues to drip - before it all gets a liberal coating of mud underneath at the Birthday Bash on Saturday! :D :D :D
Cheers,
Nick