Isabella de Say was an Anglo-Norman heiress. Isabella was the only surviving child of Helias de Say

Helias de Say

Helias de Say , also called Hellias, was a Norman nobleman who lived in Clun near Shrewsbury, along the medieval Welsh Marches. He is believed to have inherited Clun Castle from his father, Henry de Say, in the reign of Henry I. Helias held the key fortification of Clun Castle during the years of...

 upon his death in 1165; Helias was the third lord of Clun

Clun

Clun is a small town in Shropshire, England. The town is located entirely in the Shropshire Hills Area of Outstanding Natural Beauty. The 2001 census recorded 642 people living in the town...

, a powerful Norman stronghold in Shropshire, England

Shropshire

Shropshire is a county in the West Midlands region of England. For Eurostat purposes, the county is a NUTS 3 region and is one of four counties or unitary districts that comprise the "Shropshire and Staffordshire" NUTS 2 region. It borders Wales to the west...

, along the Welsh border. She was also a niece of the influential Robert, 1st Earl of Gloucester

Robert, 1st Earl of Gloucester

Robert Fitzroy, 1st Earl of Gloucester was an illegitimate son of King Henry I of England. He was called "Rufus" and occasionally "de Caen", he is also known as Robert "the Consul"...

. She is notable for helping to create the powerful medieval house of the Fitz Allans. Isabella married William Fitz Alan

William Fitz Allan, Lord of Oswestry

William Fitz Allan was a Norman noble, the eldest son of Alan fitz Flaad and the lord of Oswestry.William married Isabella de Say, the niece of Robert, 1st Earl of Gloucester...

, the lord of nearby Oswestry

Oswestry

Oswestry is a town and civil parish in Shropshire, England, close to the Welsh border. It is at the junction of the A5, A483, and A495 roads....

, as his second wife. William died in 1160, leaving a son by Isabella, William Fitz Alan II

William Fitz Alan, 1st Lord of Oswestry and Clun

William Fitz Alan was a Norman nobleman who lived in Oswestry and Clun, near Shrewsbury, along the medieval Welsh Marches. William was the son of William Fitz Alan and Isabella de Say; he was the first Fitz Alan to hold both the castles of Clun and Oswestry in his own right, and was responsible for...

. Isabella passed Clun Castle

Clun Castle

Clun Castle is a ruined castle in the small town of Clun, Shropshire. Clun Castle was established by the Norman lord Robert de Say after the invasion and went on to become an important Marcher lord castle in the 12th century, with an extensive castle-guard system...

 to him. The combined lordship of Oswestry and Clun was a significant power in the borderlands with Wales.

Isabella had married Geoffrey de Vere II, brother of the earl of Oxford by early 1166. After de Vere's death in 1170 she married William Boterel, probably by 1175, the year her son William reached his majority. She was certainly married to him by 1188. Isabella's death date is disputed, but she probably lived to 1199.

A charter of Isabella's to Much Wenlock Priory

Much Wenlock Priory

Much Wenlock Priory is a ruined 12th century monastery, located in Much Wenlock, Shropshire, at . The foundation was a part of the Cluniac order, which was refounded in 1079 and 1082, on the site of an earlier 7th century monastery, by Roger de Montgomery...

in Shropshire, purportedly issued on her deathbed, granted the church and chapels of Clun to that monastery. Her grant was confirmed by her third husband William Boterel,