Court over a car accident please help

Hey all really would appreciate some help.

Around 6 months ago I was in a slight car accident it was a bump only. No damage to either cars. The other person said they didn't want to go through insurance as no damage therefore I didn't contact my insurance. Queue to today I receive a letter from court from the claimant claiming £3.5k in damages and they're requesting I accept liability. This is not through the insurance. I have images of the car and no damage whatsoever. Where do I proceed from here?

Any help is greatly appreciated