Jeremy Morris found in the 1950s that London's double-decker bus drivers were more likely to die from cardiovascular disease than the busconductors, and that government clerks were more likely to die than mail carriers.
And anyway, there's always fun to be had laughing at the busconductors as they try to work out how much their 750, 000 Zimbabwe dollar notes add up to, and how much change they owe the passengers.