"One of the most American of British crime thrillers, combining pace, violence, and a Naked City-like use of London locations, The Informers was considered such a strong film at the time that it was awarded the new 'X' (Adults Only) certificate by the British censors, who were admittedly at their most sensitive and vulnerable at that time. It's hardly as shocking a film as that label implies, but it is a powerful and exciting crime melodrama done with unusual expertise for the British, and with Nigel Patrick surprisingly (but effectively) cast in a role resembling Glenn Ford's traditional film noir persona." William K. Everson