Noble 1787, pp. 11–13 explains the reason for Sir Richard Williams, the great grandfather of Oliver Cromwell, changing his name, from Williams to Cromwell: "Henry VIII strongly recommended it to the Welsh (whom he incorporated with the English) to adopt the English practice in taking family names, instead of their manner of adding their father's, and perhaps grandfather's name to their own Christian one with nap or ap, as Morgan ap William, or Rich, ap Morgan ap William; i.e. Rich, the son of Morgan the son of Will, and the king was the more anxious as it was found so inconvenient in identifying persons in judicial matters. For these reasons, the Welsh, about this time, dropped the ap in many of their names; or, if it could be done with convenience as to pronunciation, left out the a, and joined the p to their father's Christian name (Camden's remains; from which it appears that many Christian names were appropriated to families; for the reasons above "we have the Williams's, Lewis's, Morgans, &c. &c. without number, and, by joining the p, the Pritchards, Powels, Parrys, i. e. ap Richard, ap Howell, ap Harry, &c. &c.). Thus Mr. Morgan ap William, Sir Richard's father, seems, from the pedigree, to have taken the family name of Williams; but, as the surname of Williams was of so late standing, his majesty recommended it to Sir Richard, to use that of Cromwell, in honour of his uncle Thomas Cromwell, 1st Earl of Essex, whose present greatness entirely obliterated his former meanness (Various lives of Oliver, lord protector, &c. as also miss Cromwell's pedigree); and it is observable, that Sir Richard's brothers also changed their name to Cromwell (Will of Sir Richard Williams, alias Cromwell, prerogative-office, London, Allan 20. Pedigree of the Williams's, alias Cromwells, Harl. M.S.S. vol. 1174, and Harl. M.S.S. vol. 4135). Thus did the Williams's take, or super-add the surname of Cromwell to that of Williams; and, in almost all their deeds and wills, they constantly wrote themselves Williams, alias Cromwell, down to the seventeenth century. Though the cause of this change is well known, the time is not: many writers pretend the name of Cromwell was not taken up until the time that Sir Richard, was knighted during a tournament; but this is certainly erroneous, as there are grants of ecclesiastical lands patted to him by his names of Williams, alias Cromwell, as early as 1538: these authors are equally mistaken in supposing that the king never knew Sir Richard until the tournament, which cannot be; because those very grants patted some time before these martial games. With the name of Cromwell, Sir Richard assumed the arms of that family; but Sir Henry, his son, and his descendants, retook the proper arms of the Williams's, and never used any other (if the augmentation of the crest is excepted)".
Cokayne, G.E.; Gibbs, Vicary; Doubleday, H.A.; White, Geoffrey H.; Warrand, Duncan; de Walden, Howard (2000). The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910-1959). Vol. 3 (reprint in 6 volumes ed.). Gloucester, U.K.: Alan Sutton Publishing. p. 555. Mosley, Charles, ed. (1999). Burke's Peerage and Baronetage. Vol. 1 (106th, 2 volumes ed.). Crans, Switzerland: Burke's Peerage (Genealogical Books) Ltd. p. 1282.
