You settled on £1M, £2M , £5M, perhaps even £10 Million Liability Insurance for a reason. Because that's how much it might reasonably cost to settle a claim. Admitting a claim on grounds of efficacy, doesn't reduce the cost of any claim, it just flags up what might be a massive shortfall with the insurer chasing you or your company for the difference. That's why we say efficacy capped at £ 100,000 might be a false economy. It may tick a box, but it might not deliver on the one occasion when you need it - when you make a claim.