No genealogical records show Grimbaldus' ancestors. However, in several accounts he is claimed to be "a relative of William the Conqueror". Only one faint clue exists: the name of one of Grimbaldus' children (Ranulf) matches the lineage of the family into which William's cousin Alix of Normandy married. William's father, Robert the Devil, had a castle across the Seine from Rouen. It is therefore possible that Grimbaldus' family originated near that city.
Burke's Peerage says that "Various conjectures have been hazarded as to the origin of the surname of Bacon, but to little purpose. It matters not, however; the antiquity of the family is beyond dispute; and there are few houses in the kingdom more distinguished for the production of great and eminent men."
According to the genealogy of the Suffolk family of Bacon, one Grimbald, a relative of the Norman chieftain William de Warenne, came into England at the time of the Conquest and settled at Letheringsete near Holt in the county of Norfolk, where he had grants of land. He had three sons: Rudolf, who became the Lord of Letheringsete; Ranulf, and Edmund. The latter was appointed rector of the Church of Letheringsete, which was founded by his father. The son Ranulf, or Reynolds, resided at Thorp, Norfolk. It has been stated that he was the one who assumed the name Bacon or Bacon-Thorpe, but some authorities attribute this name to his son Roger. In any case, this appears to have been merely the assumption of an ancient Norman surname which still exists in the north of France. There were several places called Thorp in Norfolk, and Ranulf/Reynolds or Roger added the name Bacon to distinguish them from other lords of Thorp.
This family, as been said, produced a large number of eminent and learned men. Among the earliest of them was Roger Bacon, sometimes called Roger of the Black Art. He was born in 1214 and few men, if any, in that century took higher rank than he. He wrote many works both scientific and philosophical, and in 1278 his works were condemned and he was imprisoned for fourteen years.
Another Bacon at a somewhat later date was John Bacon, sometimes called Baconthorp from the name of the village where he was born. He became a learned monk and was known as The Resolute Doctor. He died in London in 1346.
Continuing to more recent times, we come to Sir Nicholas Bacon, who in the reign of Queen Elizabeth was Lord Keeper of the Great Seal. He was the first person to be created a baronet by James I. His [adopted] son was Francis Bacon, who in 1617 was himself appointed Lord Keeper of the Great Seal. In 1618 Francis himself was made Lord High Chancellor of England and the same year was created Baron Verulam and Viscount Saint Albans.
The Baronetage of England, by Kimber and Johnson, speaking of this family says: "Of this name there have been many persons of great account in former ages; but that particular family, of which we are now to treat, derive their descent from Grimbaldus who came into England at the time of the Norman conquest in company with William Earl Warren, to whom he was related, which Grimbaldus had lands in Normandy, and after his arrival in England settled at Letheringsett near Holt in Norfolk, where he founded the church and made his second son Edmund parson of it. His other sons were Radulph [sic] and Ranulf.
Again, in a genealogy of the Cleveland family compiled by Edmund James Cleveland and Horace Gillette Cleveland there is a notice of the Bacon ancestry, from which comes the following extract:
"Grimbaldus, the patriarch of the Bacon family and a Norman gentleman, came to England in 1066 with–and was related to–William de Warren, Earl Surrey, was of Letheringsete, Norfolk co[ounty] had sons, Randulph, Edmund (who each took the name of his abode thus, Ranulph de Laringsete) and Ranulf, Reynold or Ralph, who was of Thorpe, Norf. and took name Ralph de Bacons-thorpe, was founder of this illustrious family, was father of Roger (whose s. Robert assumed the name Bacon) and of George whose s. Roger was progenitor of Bacons of Drinkston and Hessett, Suffolk co[unty] ...[sic] John Bacon of H. m. Cecilly Hoo or How and had John who m. Hellen Gedding, whose s. John m. 1st Hellena Tillotts da[ughter]. Sir George of Rougham and had John who m. Margery Thorpe da. of John (s. of William by w. Margaret Quapladde) s. of Sir William Thorpe by w. Beatrix Bacon da. of Sir Roger Bacon12 (Sir Henry11 m. Margaret Ludham, Sir Henry10, Richard9, Reginald8, Richard7, Reginald6, Robert5, Roger4, George3, Ralph2, Grimbald1) commander in the wars temp. Edw. II and III, and had Edmund of Drinst, father of John, who m. Agnes Cokefield, whose s. Robert m. Isabella Cage, da. John and had Sir Nicholas (father of Lord Francis b. London, Jan. 22, 1561, Baron Verulam Hertford Co. and Viscount Saint Albans) and Alderman James of London the ancestor of Nathaniel of Virginia, 1670."