Maud, Abbess of Montivilliers was a natural daughter of Henry I of England

Henry I of England

Henry I was the fourth son of William I of England. He succeeded his elder brother William II as King of England in 1100 and defeated his eldest brother, Robert Curthose, to become Duke of Normandy in 1106...

 and his young mistress

Mistress (lover)

A mistress is a long-term female lover and companion who is not married to her partner; the term is used especially when her partner is married. The relationship generally is stable and at least semi-permanent; however, the couple does not live together openly. Also the relationship is usually,...

 Isabel de Beaumont (ca 1102 - ca 1172), herself a sister of Robert de Beaumont, 2nd Earl of Leicester

Robert de Beaumont, 2nd Earl of Leicester

Robert de Beaumont, 2nd Earl of Leicester was Justiciar of England 1155–1168.The surname "de Beaumont" is given him by genealogists. The only known contemporary surname applied to him is "Robert son of Count Robert"...

.

Born Matilda Fitzroy, her maternal grandparents were Robert de Beaumont, 1st Earl of Leicester

Robert de Beaumont, 1st Earl of Leicester

Robert de Beaumont, 1st Earl of Leicester, Count of Meulan was a powerful English and French nobleman, revered as one of the wisest men of his age...

 and Elizabeth of Vermandois. She was a half-sister of Richard "Strongbow" de Clare

Richard de Clare, 2nd Earl of Pembroke

Richard de Clare, 2nd Earl of Pembroke , Lord of Leinster, Justiciar of Ireland . Like his father, he was also commonly known as Strongbow...

, her mother's son through a marriage to Gilbert de Clare, 1st Earl of Pembroke

Gilbert de Clare, 1st Earl of Pembroke

Gilbert fitz Gilbert de Clare , son of Gilbert Fitz Richard and Alice de Claremont, was sometimes referred to as "Strongbow", although his son is better remembered by this name, was the first Earl of Pembroke from 1138....

, and of the Empress Matilda

Empress Matilda

Empress Matilda , also known as Matilda of England or Maude, was the daughter and heir of King Henry I of England. Matilda and her younger brother, William Adelin, were the only legitimate children of King Henry to survive to adulthood...

, who apparently valued her company and advice. Perhaps due to their closeness, Matilda or "Maud" is called the Sister of the Empress Matilda.

She was the abbess

Abbess

An abbess is the female superior, or mother superior, of a community of nuns, often an abbey....

 at the Abbey Church of Notre-Dame, Montivilliers

Montivilliers

Montivilliers is a commune in the Seine-Maritime department in the Haute-Normandie region in northern France.-Geography:A large light industrial and farming town by the banks of the river Lézarde in the Pays de Caux, situated just north of Le Havre, at the junction of the D489, D52, D926 and D31...

, and for that reason is best known as Maud of Montivilliers.