From the same link:
If a Third Party makes a claim against you through your insurer, they don't need to contact you about paying your excess. Unless it's very clear that you might be at fault, and depending on the amount being claimed for, your insurer might settle the claim without telling you. Especially if it's not deemed worth the insurer's time to dispute a smaller claim where it's likely to be a 50/50 shared responsibility. The other driver might then put in an additional claim for personal injuries like whiplash, and again get it settled without your knowledge. When your policy is due for renewal, you could find out claims have been logged against you, potentially increasing your premium.