Lady Isabel (Countess of Essex) (c1409 - 1484)Born: c14091
Died: October 2, 14841,2
(1) Thomas Grey1
(2) Henry Bourchier1
Father: Richard of Conisburgh - 3rd Earl of Cambridge
Mother: Lady Anne de Mortimer
William Bourchier (Viscount Bourchier)
Through her father, Lady Isabel (Countess of Essex) (c1409 - 1484) was the granddaughter of King Edward III's son, Edmund of Langley, 1st Duke of York, and his first wife, Isabella of Castile. Her mother was Lady Anne Mortimer, the great-granddaughter of Lionel of Antwerp, another son of Edward III. So Lady Isabel was both the great-granddaughter of Edward III (through her father) and the great-great-great-granddaughter of Edward III (through her mother). This situation is explained as follows: Lady Isabel's father married his first-cousin-twice-removed, who was fourteen years his junior. Both mother and father of Lady Isabel are therefore direct descendants of Edward III (1312 - 1377).
In 1412, at three years of age, Isabel was betrothed to Sir Thomas Grey who was eight years old. They later had one son. When she was still young (about seventeen years old) she married Henry Bourchier, 1st Earl of Essex. Her second marriage was later validated by papal dispensation. She had at least eight children from the second marriage1. One of her sons, William Bourchier (Viscount Bourchier; d. 1480), is the great-great-great-great-great-great-great-great-grandfather of Jane Calvert (1736 - 1819)2.
Isabella Perez de CastileIsabella of Castile (c1355 - 23 December 1392)3 was the grandmother of Lady Isabel (Countess of Essex) (c1409 - 1484). She was the youngest of the three daughters of King Pedro 'the Cruel' of Castile and María de Padilla. Isabella married on 11 July 1372 and had three children. She died 23 December 1392 at the age of about 37 and was buried at the church of the mendicant friars at Kings Langley, Hertfordshire, England. The remains were reburied at All Saints Churchyard, King's Langley. In 1877, Professor George Rolleston exhumed the grave and found the remains of Isabella of Castile, her husband Edmund of Langley and their daughter-in-law Anne Mortimer.
Sources1. The Peerage: Isabella Plantagenet
2. Plantagenet family tree (Edward III to Jane Calvert) from: The Plantagenet Roll of the Blood Royal (The Isabel of Essex Volume) The Genealogical Publishing Co. Ltd. London (click image to enlarge)
3. The Peerage: Isabella of Castile Grandmother of Lady Isabel Plantagenet Countess of Essex