He replaced the filter. I provided it and checked it on the weekend - it was a Ryco SynTec which are black.
To be honest I don't know what he did, but I do know he replaced the filter. Instead of just owning his error (saying he overfilled it) he convinced me he was right and maybe the dipstick was replaced with a different one when it was getting serviced by ford. The idea is it might have been serviced by an apprentice that wasn't paying attention etc. I believed him because I didn't think he had any reason to lie. When I went back about it he was almost having a giggle. He was lucky not to cop a flogging - he didn't get one only because I would have been in more trouble than it is worth (the wife views those sort of things pretty poorly).
I replaced the oil and filter again on the weekend, for my own piece of mind mainly. It is all OK now.
Goes to show if you want something done right.....