No claim bonuses are bullshit. If you claim and they say it doesn't effect your no claim bonus, they still give you the full bonus but they put your premiums up to offset it. The explanation.. because now you've claimed you are in a higher risk category, "but you get to keep your no claim bonus so what's the problem?" they'll ask you. I know that like for like i.e. identical vehicles insured for identical amounts with both dirvers on 65% the premium difference after bonus for the incident described above is a about 10% for probably 5 years on all the vehicles you have insured. See, no claim bonuses are bullshit.
Of course, don't take my work, ask your insurer.