I don’t think you can assume hotel guests who use the car park will follow commuter patterns of usage. Why would they all be coming out at the same time? They’ll be going different places, to arrive at different times. Some will be tourists using FH as a cheap base and mostly using public transport into central London and only exiting the car park at the end of their stay. Some business users will be doing the same.
Inclined to agree- although I think most people would come by public transport. Business users driving in would still have to make an arduous journey though one part of London or another. Those driving seem to stay further out in places with good connections in my (limited) experience- near City airport for example.