I've done this a few times (both as bumper and bumpee!) and I find most people are fairly genuine. Did you take a photo of his car as proof? As long as you've got his registration number, your insurance company would find him if everything went pear shaped. From what you describe, if he asks for about �100 - �150 (if less, you are quids in), that would be about right. If this all works out OK, send with the cheque a letter for him to sign and return to you (include an SAE) saying that this payment is in full and final settlement of any claim on the date against his vehicle reg.