ɡɹˈɛnvɪl wʌzðɪ ˈɛldɪst sˈʌn ʌv dʒˈeɪmz ɡɹˈɛnvɪl ˌɛmpˈiː twˈɛlv fˈɛbɹuːˌɛɹi wˈʌn θˈaʊzənd sˈɛvənhˈʌndɹɪd fˈɪftiːn fˈoːɹtiːn sɛptˈɛmbɚ wˈʌn θˈaʊzənd sˈɛvənhˈʌndɹɪd ˈeɪɾi θɹˈiː ænd ɐ fˈɜːst kˈʌzən ʌv dʒˈɔːɹdʒ nˈuːdʒənttˈɛmpəlɡɹˈɛnvɪl, fˈɜːst mˈɑːɹkwɛs ʌv bˈʌkɪŋˌæm.
Grenville was the eldest son of James Grenville MP (12 February 1715 – 14 September 1783) and a first cousin of George Nugent-Temple-Grenville, 1st Marquess of Buckingham.