Damage to grey BMW 1 Series on Saturday 9/9/23

My son's car LM62YBS (Grey 1 Series BMW) arrived 10.30 am Saturday morning and was parked carefully facing the estuary in the middle section of car park under trees and placed deliberately well away (seaward) from club house so as not to cause obstruction. Car park was virtually empty at that time. Damage was to rear nearside door, sill and wheel arch. He's sure it happened at SYC as he had been checking tyre pressures the day before and that morning due to a faulty tyre pressure dash read out. Vehicle was left overnight 9/9. He's had the car a week.  Damage was seen 10am 10/9. I'm guessing Saturday midday and evening  at SYC would have been busy due to the especially warm weather. Quite possible the driver may not even have known it had happened .....especially if caused by a larger vehicle or trailer. Also likely there's grey paint on whatever caused it! Has anybody any insight into this please? (Cannot upload photos of damage as they exceed max file size of 500kb) Thanks. SCP