It's probably too late for that, as the insurers now ask whether you've had any accidents within the last X years, rather than whether you've made any claims within the last X years.Having seen how much insurance has risen for my Wife who has had no claims in the last year, I'd be trying to pay it personally rather than risk losing any NCB!!
In other words, the OP should admit to the accident come renewal time, whether or not it was put through as a claim. Not admitting to it, especially now that the insurers know that it has happened, would give them a massive "Get Out Of Paying Free" card if they need one in future.