MrTurner said:
If he's not reported it to his insurer, technically he's breaking the law.
Er, no, he very much isn't.
To clarify some things that are starting to get muddled, there are several issues to consider:
1. Statutory obligation;
2. Contractual obligation;
3. Claiming insured losses;
4. Claiming uninsured losses.
Legal obligation
If your vehicle is involved in an accident on the public highway then you are obliged to give your personal contact details,
and your insurance details, to anyone who reasonably makes a request for them. If you can't do it at the roadside then you must do so within a period (which I believe to be 24 hours) afterwards, or you must report the accident to the police instead of contacting the third party. If anyone is injured then you must report the accident to the police anyway.
Contractual obligation
The terms of your insurance policy will, without doubt, require you to report any accident to them where you are involved as a driver, whether or not it's your fault, whether or not there was any damage, and whether or not you have comprehensive insurance. They usually impose a time limit, if you're claiming, and it's usually 30 days.
Claiming insured losses
If you have comprehensive insurance then you have a choice:
a) Let your insurance company handle everything.
Since you'll be reporting the accident to them this is what most people do, but be aware that can increase the risk of you incurring an uninsured loss, i.e. any policy excess that you have - see below.
The risk increases in small incidents because the two insurance companies involved might agree to cover their own losses - this is known as a knock-for-knock arrangement - in order to minimise the administrative overheads. If you are confident that the other driver can be shown to be culpable, and you want to eliminate this risk, then don't claim through your insurance company - simply notify them and tell them that you will be handling the claim for damage to your car.
b) Act as though you didn't have comprehensive insurance, and see below for claiming uninsured losses.
Claiming uninsured losses
If you don't have comprehensive insurance, or if you decide to go it alone, then immediately write to the other party holding them fully liable, and request details of their insurers (if you haven't already been given them). From this moment onwards put everything in writing, keep copies, stay polite, but be prepared to go to court.
If you lose a civil claim then be aware that you'll probably expire the time limit within which you may claim through your own insurance company, so only choose this route if you are confident.