Another common misconception is that you do not have to report accidents that were not your fault to your insurer. You should definitely report any accident that involves your car, however small, to your insurer, even if it was not your fault. In fact, failing to report even a minor accident can mean your car insurance agreement could be invalidated by your insurer and they may fail to pay out on a claim.
Almost every insurance company includes clauses in their policy which require you to report any incident from the past five years, even if it happened in a vehicle that was not your own such as a company car or fleet car. Failure to declare something would be deemed as non-disclosure, which can invalidate your policy.
Your no-claims discount will not be affected if you report a non-fault accident. Unfortunately, however, your future premiums probably will be increased, as an insurer will likely consider you a higher risk, even if you were not the at-fault party.