Tacitus on The Emperor Galba: “Omnium consensu capax imperii nisi imperasset.” “All pronounced him worthy of the empire, until he became emperor”.
I’d like to be erudite enough to be able to claim that as an original observation, but it was actually suggested in an otherwise dull comment to Phillip Hensher’s exceedingly suckyuppy Independent column praising the newly-powerful Boris for his use of classical allusions.