The insurance company may insist you tell them of all accidents, even if it was sorted amicably totally outwith the insurance. And if you declare it, they WILL increase your premium, even if it wasnt your fault, even if the car was parked on the road and you were tucked up in the house watching the TV. You've had an accident/claim, that makes you more risky statistically than someone who hasnt.

However, if it was all done and sorted outside the insurance, they have NO record of the accident, so unless you go blabbing about it to them, they dont know, and will never know it happened.