Our drive was blocked all day too by some kind considerate person, so I am glad to see it wasn't just me suffering.
I don't think they should necessarily move it from the Horniman, but they could at least warn local residents as I had no idea it was happening and would have gone out for the day if I had known so that I didn't have to listen to cars honking all day outside on Honor Oak Road.
Interestingly one of the cars who blocked our driveway just backed into another car behind them when they were leaving without a second glance and drove off...nice!