ɪn nˈaɪntiːnhˈʌndɹɪd twˈɛnti tˈuː, ˈɛkspɜːts tˈɛstᵻfˌaɪd ðætðə ɡɹˈɪnəlz hɐdbɪn pɹədˈuːst baɪ fˌoʊɾoʊɡɹˈævjʊɹ ænd nˌɑːt baɪ hˈændsɛt mˈuːvəbəl tˈaɪp, bˌʌt ɪnðə nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi z kˈiːθ kˈɔːɹdɹi kəntˈɛndᵻd ðæt ðeɪ wɜː pɹˈɑːbəbli tˈaɪpsɛt, ænd ðə ɹˈɔɪəl fɪlɐtˈɛlɪk səsˈaɪəɾi lˈʌndən ɐɡɹˈiːd.
In 1922, experts testified that the Grinnells had been produced by photogravure and not by handset moveable type, but in the 1980s Keith Cordrey contended that they were probably typeset, and the Royal Philatelic Society London agreed.