As you may know, Vermeers are so few and far between that it's entirely possible to see every one (~36) if you're able to travel the world.
So, there exists a subculture of (often) wealthy Vermeer completeists who travel the world doing exactly that.
Every month or so at Kenwood, we would be instructed to come in early to host such collectors who had made arrangements for a private viewing of this Vermeer.
An entourage would roll up around 6-7am to whisk a high-flyer into the room the Vermeer was displayed.
More often than not the individual - who was so determined to see this painting they'd paid English Heritage who knows how much - took a momentary glance and was off again.
I'm talking all that trouble for 1-2 minutes in front of the Vermeer so they could check it off their list. And then they were off.
I'd happily spend the next 8 hours in front of it observing public responses and daydreaming of how to prevent elaborate art thefts (the painting was stolen by the IRA in 1974 and IMHO could certainly be stolen again).