The envelope

I droped of my fare and looked at my data head and there was plenty of work to be had up town,Half way there the operator contacted me on the radio and asked me if my last customer had left an envelope in the car.I had a quick look around and found it....empty.Great im going to have to travel back through town to drop off an empty brown envelope during rush hour too.When i got there he gave me some money for my trouble so i mentioned it was strange him paying another taxi fare just for an envelope thats worth a couple of pence.He said it wasnt empty and i thought great hes going to say ive took the contents.He then pulls out a 20p piece and says nope its still there.Im then thinking this guy is either nuts or taking the piss until he shows me the coin apparently the royal mint have made a load of 20p that have no date on them and coin cllectors are paying good money for them.This particular coin had just been sold on ebay for £150.I quickly pulled up around the corner and started going through my float at the speed of 1000 racing snakes well you never know do you!!