BBC History magazine had a poll on the 'Greatest Prime Minister' recently. The organiser of the poll - although left of the centre - put Thatcher well up on the list. Aparently in this context'greatest' meant 'had the greatest effect.' Using that meaning of the word then A. Hitler was the greatest leader ever!

A book of lists I browsed somewhere had a list of the worst person ever year by year; it went: ...Hitler, Hitler, Hitler, Nixon, Nixon, Nixon, Hitler etc...

DocJ