Looks to be a taxi (or ex-taxi) from Crewe, though it doesn't have the taxi licensing number plate which is required for all private-hire taxis to be displayed in the UK (probably would be displayed next to the rear license plate in this case). Interesting spot, though I could imagine the fare wouldn't be cheap to southern France from Cheshire!
This was a private underground parking so probably the owner of the taxi brought his family to vacation with it. Still very interesting to see an English taxi in the French Riviera!