Extint and Dormant Baronetcies of England, Ireland, and Scotland., John Bernard Burke, Esq. 2nd Ed. London, 1844, page 498
Lineage: This was a branch issuing from the stock of the noble houses of Marlborough and Spencer. William Spencer, esq. of Redburn, in the county of Warwick, anno, 1 Henry VII who married Elizabeth, sister of Sir Richard Empson, knt. and had, with a daughter Jane, two sons, John and Thomas.
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Note: During the Renaissance, an unscrupulous herald manufactured a spurious genealogy tracing the Spencers of Althorp back to the Despensers of Winchester, but that fictitious genealogy was long ago debunked -- there is no proof, nor any reason to believe, that the Spencers of Althorp had anything to do with the old Earls of Winchester.