I think the driver of the BMW whose front wing was mangled would dispute there was no damage. I don't want to harp on about this but I do think you are wrong John. Damage to anything other than damage to that vehicle which caused the accident, i.e. any one of the cars involved (or mechanically propelled vehicle as the act so succintly puts it). If there is no damage to either car and the drivers agree to waive it then yes, it is okay not to report it, but in this case there is damage. You may not want the police involved but as someone above said, it is an offence not to report an accident that involves damage.