Children

1. Thomas Clifford, 8th Baron de Clifford m. Joan Dacre, daughter of Thomas Dacre, 6th Baron Dacre and Philippa de Neville.
2. Henry Clifford.
3. Mary Clifford m. Philip Wentworth, Knight, of Nettlestead, Suffolk; Their great-granddaughter was Jane Seymour, third Queen consort of Henry VIII of England.
4. Blanche Clifford.

Sources

1. Thomas Blore (1811). The History and Antiquities of the County of Rutland. Stanford: R. Newcomb.
2. G.E. Cokayne; with Vicary Gibbs, H.A. Doubleday, Geoffrey H. White, Duncan Warrand and Lord Howard de Walden, editors, The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910-1959; reprint in 6 volumes, Gloucester, U.K.: Alan Sutton Publishing, 2000), volume XII/2, page 550, 549
3. Cokayne, and others, The Complete Peerage, volume III, page 293.

another possible death date is 25 October 1437

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http://en.wikipedia.org/wiki/Lady_Elizabeth_Percy

http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=60731704

http://www.genealogy4u.com/genealogy/getperson.php?personID=I329&tree=western2007

http://thepeerage.com/p1053.htm