I think Id be inclined to let it rest now Graham. If you claim of your insurance, despite NCB, I suspect your renewal will reflect the claim. Whether you claim or not, the incident is now recorded on the industry database, and you will have to report it it to any future prospective insurer when seeking insurance. A few years ago, a woman e stopped in front of me for no reason, I grabbed a fistful and the front wheel slipped under me on loose chippings and tumbled onto its side, speed was no more than 5mph. The driver claimed against me for hitting the rear of her car, despite the driver behind me telling her I was at least a metre from her bumper when stopped. We swapped details, she drove off, the witness drove off, and I thought no more of it, until the claim against me dropped through the letter box. I immediately insisted on a full engineers assessment of the bike, which conclude that there was no evidence of any frontal impact , other than scratches on the offside engine guard, as a result of the bike dropping on its side at low speed. My insurer settled he claim against me, despite the report, simply because it was cheaper for them to do so rather than fight it. I was foccin outraged, being convicted despite any evidence against me, and told them in the strongest words I could find in the dictionary, both the claims handler and the insurance company. The industry stinks, but we have to use it.
I strongly sympathise, but I reckon there's little you can do