As it's only 20 buses out of over 8000, you're not too likely to spot one on a visit. They are marked, but they're still red buses that don't look much differe

As it's only 20 buses out of over 8000, you're not too likely to spot one on a visit. They are marked, but they're still red buses that don't look much different to the rest. London restricts the way public buses can be painted (mostly red), and even efforts like this don't seem to be exempted. https://commons.wikimedia.org/wiki/File:First_London_fuel_cell_bus_WSH62995_%28LK60_HPN%29_VDL_SB200_Wrightbus_Pulsar,_Catherine_Street,_route_RV1,_20_May_2011.jpg https://commons.wikimedia.org/wiki/File:First_London_fuel_ce...