Conspicuous by one’s absence

This expression was coined by Lord John Russell (1792-1878) in a speech to the electors of the City of London in 1859, “Among the defects of the bill, which were numerous, one provision was conspicuous by its presence and another by its absence.” Lord Russell said it was inspired by something he had read in Tacitus Annals describing the funeral of Julius Caesar, at which Brutus and Cassius were not present. Their absence focused everyone’s attention, conspicuously.