Your colleague is misadvising you. The car is not recorded/registered as being involved in an accident, as such that on its own will not decrease its value. What your colleague may be talking about is Diminution in Loss". This basically means that if you have been involved in an accident that was not your fault, then it could be argued your vehicle has been “reduced” in value due to being damaged and now repaired (even when repaired to a perfectly satisfactory standard).

The case law around it is based on a case called “Payton-v-Brooks” 1974 where it was argued that, if you have two vehicles at a point of sale, that the one that had the connotation of being involved in an accident, would be worth less than one that had.

This set legal precedent, meaning that it is a legal header of a claim that you can claim for. It is a complicated arena. You are always entitled to claim for Diminution in Loss, however, the level of diminution achieved may not make it worthwhile claiming or a court may frown upon a low-value claim being submitted. The level of diminution is related to the type of vehicle, extent of damage and other variables.