hiː ɛksplˈeɪnz ðˌɐɾɪt bɪɡˈæn ɐpˈɪɹɪŋ ɪn bɹˈɪɾɪʃ lˈɪɾɚɹᵻtʃɚɹ ɪnðə nˈaɪntiːnhˈʌndɹɪd fˈɪfti z, ɔːlðˈoʊ ðɪ ɐmˈɛɹɪkənz ðˈɛn "sˈiːmd tə lˈuːz tɹˈæk ʌvðə tˈɜːm".
He explains that it began appearing in British literature in the 1950s, although the Americans then "seemed to lose track of the term".