A very good question. Technically yes and technically no. As you were not 'in charge' of your vehicle at the time - and the vehicle was covered under a different policy of insurance (the garages), then that is your technically no answer. The insurer will advise otherwise. What I would do is contact your insurer and ask the question. Unfortunately every claim handler you speak to will not know the answer and would have to refer to the default 'yes you must make us aware of any incident you have been involved in.' What would I do? Well it would be unfair of your insurer to penalise you in any way as result of an incident which was not your fault, and you were in no way connected. If I was asked the next year had I had any accidents or claims, my answer would be no. As it was the repairers claim not yours. They were acting as a bailee.