æz ɐ ɹɪzˈʌlt ʌv ðɪs wˈɜːk, hiː bɪkˌeɪm ɐ fɹˈiːkwənt ɐdvˈaɪzɚ tə ðə tʃaɪnˈiːz ɡˈʌvɚnmənt, ɪŋklˈuːdɪŋ ðə wˈɑːʃɪŋtən nˈeɪvəl kˈɑːnfɹəns ɪn nˈaɪntiːnhˈʌndɹɪd twˈɛnti wˈʌn ænd ðə tˈuː ˈoʊpiəm kˈɑːnfɹənsᵻz ɪn dʒənˈiːvə ɪn nˈaɪntiːnhˈʌndɹɪd twˈɛnti fˈoːɹ nˈaɪntiːnhˈʌndɹɪd twˈɛnti fˈaɪv ænd ɐɡˈɛn ɪn nˈaɪntiːnhˈʌndɹɪd θˈɜːɾi wˈʌn, wˌɛɹ wˈɪlʌfbi ˈɔːlsoʊ sˈɜːvd æz ɐn ɐdvˈaɪzɚ tə ðə tʃaɪnˈiːz dˌɛlɪɡˈeɪʃən tə ðə lˈiːɡ ʌv nˈeɪʃənz.
As a result of this work, he became a frequent advisor to the Chinese Government, including the Washington Naval Conference in 1921 and the two Opium Conferences in Geneva in 1924–1925 and again in 1931, where Willoughby also served as an advisor to the Chinese delegation to the League of Nations.