Before 13 Oct 1370 [her father] Thomas Holland 2nd Earl Kent (age 20) and [her mother] Alice Fitzalan Countess Kent (age 20) were married. She by marriage Countess Kent. She the daughter of Richard Fitzalan 10th Earl Arundel 8th Earl Surrey (age 64) and Eleanor Plantagenet Countess Arundel and Surrey (age 52). He the son of Thomas Holland 1st Earl Kent and Joan "Fair Maid of Kent" Princess Wales (age 42). They were third cousins. He a great grandson of King Edward "Longshanks" I of England. She a great x 2 granddaughter of King Henry III of England.

On 11 Jul 1372 [her future husband] Edmund of Langley 1st Duke York (age 31) and Isabella of Castile Duchess York (age 17) were married at Wallingford, Oxfordshire [Map]. She by marriage Countess Cambridge. She being the younger sister of Constance (age 18) who had married Edmund's older brother [her future brother-in-law] John of Gaunt 1st Duke Lancaster (age 32) a year before. An example of Marriage of Two Sets of Siblings. She the illegitmate daughter of Peter "Cruel" I King Castile and Maria Padilla. He the son of King Edward III of England (age 59) and Philippa of Hainault Queen Consort England.

After 03 Jan 1383 [her future husband] William Willoughby 5th Baron Willoughby (age 13) and Lucy Strange Baroness Willoughby Eresby were married. They were third cousins.

On 04 Nov 1393 Edmund of Langley 1st Duke York (age 52) and Joan Holland Duchess York (age 13) were married. She by marriage Duchess York. The difference in their ages was 38 years. She the daughter of Thomas Holland 2nd Earl Kent (age 43) and Alice Fitzalan Countess Kent (age 43). He the son of King Edward III of England and Philippa of Hainault Queen Consort England. They were half second cousin once removed. She a great x 2 granddaughter of King Edward "Longshanks" I of England.

Before Jul 1396 [her future brother-in-law] Thomas Willoughby (age 16) and Elizabeth Neville (age 12) were married. They were step-brother and sister since his father Robert Willoughby 4th Baron Willoughby (age 47) married her mother Elizabeth Latimer 5th Baroness Latimer, Baroness Neville and Willoughby in 1388. She a great x 5 granddaughter of King Henry "Curtmantle" II of England.

Before 11 Jul 1398 [her future husband] Henry Scrope 3rd Baron Scrope Masham (age 25) and Phillipe Bryan Baroness Scrope Masham Baroness Devereux were married. She by marriage Baroness Scrope Masham. They were third cousin once removed.

Before 07 Oct 1398 [her step-son] Edward York 2nd Duke of York 1st Duke Albemarle (age 25) and Philippa Mohun Duchess Albemarle aka Aumale Duchess York (age 31) were married. He the son of Edmund of Langley 1st Duke York (age 57) and Isabella of Castile Duchess York. He a grandson of King Edward III of England.

Before 09 Aug 1404 William Willoughby 5th Baron Willoughby (age 34) and Joan Holland Duchess York (age 24) were married. She by marriage Baroness Willoughby de Eresby. She the daughter of Thomas Holland 2nd Earl Kent and Alice Fitzalan Countess Kent (age 54). She a great x 2 granddaughter of King Edward "Longshanks" I of England.

In May 1406 [her former step-son] Richard of Conisbrough 1st Earl Cambridge (age 20) and Anne Mortimer (age 15) were married. The marriage apparently took place in secret possibly because she was a descendant of King Edward III of England although she wasn't at the time Heir to the Throne of England although their issue would become so. She died five years later. She the daughter of Roger Mortimer 4th Earl March 6th Earl Ulster and Eleanor Holland Countess March and Ulster. He the son of Edmund of Langley 1st Duke York and Isabella of Castile Duchess York. They were first cousin twice removed. He a grandson of King Edward III of England. She a great x 2 granddaughter of King Edward III of England.

Before 18 Nov 1406 William Fitzhugh 4th Baron Fitzhugh (age 7) and [her step-daughter] Margery Willoughby Baroness Fitzhugh (age 9) were married. He the son of Henry Fitzhugh 3rd Baron Fitzhugh (age 48) and Elizabeth Grey Baroness Fitzhugh (age 42).

After 06 Sep 1410 Henry Scrope 3rd Baron Scrope Masham (age 37) and Joan Holland Duchess York (age 30) were married. She by marriage Baroness Scrope Masham. She the daughter of Thomas Holland 2nd Earl Kent and Alice Fitzalan Countess Kent (age 60). She a great x 2 granddaughter of King Edward "Longshanks" I of England.

After 21 Sep 1411 [her former step-son] Richard of Conisbrough 1st Earl Cambridge (age 26) and Maud Clifford Countess Cambridge (age 22) were married. He the son of Edmund of Langley 1st Duke York and Isabella of Castile Duchess York. He a grandson of King Edward III of England. She a great x 4 granddaughter of King Edward "Longshanks" I of England.

Before 27 Apr 1416 Henry Bromflete 1st Baron Vesci (age 9) and Joan Holland Duchess York (age 36) were married. There appears to be a twenty-seven year age gap here which may suggest the marriage ewas a reward to him since she, having being married three times before, including to Edmund of Langley 1st Duke York, would be a wealthy widow. The difference in their ages was 26 years; she, unusually, being older than him. She the daughter of Thomas Holland 2nd Earl Kent and Alice Fitzalan Countess Kent (deceased). She a great x 2 granddaughter of King Edward "Longshanks" I of England.

Before 14 Aug 1418 [her former brother-in-law] John Scrope 4th Baron Scrope Masham (age 30) and Elizabeth Chaworth Baroness Scrope Masham (age 27) were married. She by marriage Baroness Scrope Masham. They were fourth cousins.

Before 21 Feb 1421 [her former step-son] Robert Willoughby 6th Baron Willoughby (age 36) and Elizabeth Montagu Baroness Willoughby Eresby (age 21) were married. She by marriage Baroness Willoughby de Eresby. She the daughter of John Montagu 3rd Earl Salisbury and Maud Francis Countess of Salisbury (age 57). She a great x 3 granddaughter of King Edward "Longshanks" I of England.