kɹˈɪstəfɚɹ ˈændɹuː, ɪn hɪz hˈɪstɚɹi ʌvðə kˌeɪdʒˌiːbˈiː, dᵻskɹˈaɪbd smˈɪθ æz "pɹˈɑːbəbli ðə mˈoʊst ɪmpˈoːɹtənt bɹˈɪɾɪʃ lˈaɪn ˈɛks ˈeɪdʒənt sˈɪns ðə ɹᵻtˈaɪɚmənt ʌv mɛlˈiːɾə nˈoːɹwʊd".
Christopher Andrew, in his history of the KGB, described Smith as "probably the most important British Line X agent since the retirement of (Melita) Norwood".