Update: North Yorks Police (where the car is registered) would not 'have a word' with the driver without a statement, so I gave one in Driffiled on Sunday. They then spoke to the registered keeper today, they admitted driving the car on the road at that time on that day, and overtaking a vehicle at the very point I described. They stated they never saw a cyclist at all, and would not have overtaken had they seen me. They accepted police words of advice ref. their driving, and asked for their appologies to be passed on to me. Being an ex-copper, I know that without any independant witnesses that is the best result I could have hoped for.
Case closed, it just goes to prove it pays to complain, and be realistic about possible outcomes with no independant witnesses or cctv etc.