Each summer, wealthy supercar owners from Middle Eastern countries including Saudi Arabia, Kuwait and Qatar arrive in London for their annual holiday to escape the sweltering heat back home.
They bring with them their luxury cars, shipped over to the capital at a huge cost, for the so-called supercar “season” before driving around affluent areas of London including Knightsbridge and outside luxury department store Harrods.
I strongly suspect that this one wasn't unplanned, more a case of the people who left the cars there not caring about some poxy parking fines.
https://www.standard.co.uk/news/london/smiling-passersby-look-on-as-2m-fleet-of-supercars-parked-in-covent-garden-are-all-slapped-with-a3616991.html
I still find it an interesting social phenomenon: