John Spencer, Esq., MP for Dorset

Not a known son of Lady Margaret le Despenser

https://en.wikipedia.org/wiki/Robert_Spencer_of_Spencer_Combe

The American genealogist Douglas Richardson[5] suggests that Sir Robert Spencer (d. bef 1510) was in fact the son and heir of John Spencer, Esquire, MP for Dorset, of Frampton in Dorset, Ashbury in Devon and Brompton Ralph in Somerset, by his wife Jone.

Douglas Richardson believes that Robert Spencer's parents were John Spencer, Esq. and Joan/Jone [unknown].

Here is his comment from the GEN-MEDIEVAL-L Archives:

The following two Chancery lawsuits prove that Sir Robert Spencer was the son and heir of John Spencer, esquire, by his wife, Joan.

C 1/160/2: Robert Spenser, knight, son and heir of John Spenser, esquire. v. Robert Cotes, feoffee to uses.: A moiety of the manor of Brompton Ralph and the advowson of the church.: Somerset. Date: 1486–93, or 1504–1515.

C 1/480/13: Thomas, son and heir of William Cary and of Alice, his wife, daughter of Baldwin Folford, knight. v. John Fuleford, esquire.: Detention of deeds relating to the manor of Ashbury, Devon, and half the manor of Brompton Ralph, Somerset, claimed by complainant in right of Margaret, his wife, daughter and heir of Robert Spencer, knight, son and heir of John Spencer and of Joan, his wife. Date: 1518-1529

The above Chancery lawsuits indicate that Sir Robert Spencer's family held land interests in Ashbury, Devon and Brompton Ralph, Somerset, but not at Spencercombe, Devon. The evidence such as it is unclear where Sir Robert Spencer actually resided. There are various records generated by Sir Robert and his wife, Eleanor, during their marriage, but none indicate a residence for Sir Robert Spencer. Until now, all that is known, is that Sir Robert Spencer was living at Chilton Foliat, Wiltshire at the time he made his will, which will was proved 12 April 1510 (P.C.C. 27 Bennett).

More at link:

http://archiver.rootsweb.ancestry.com/th/read/GEN-MEDIEVAL/2013-07/...

See also this site, which mostly uses Richardson as a source:

http://our-royal-titled-noble-and-commoner-ancestors.com/p513.htm

WikiTree and ThePeerage.com don't show known parents for Robert Spencer--see notes and sources at links.