As previously mentioned, I believe that you do have to notify your Insurance company, failure to do so could be considered as non-disclosure for any future insurance, also I do believe that unfairly as it sounds, its a No claims bonus and not a No blame bonus, so you could lose this also, even though its not your fault - worth checking with your insurers and I would be careful, as its amazing how many times people accepting blame change their minds when their Insurer becomes involved.