D'Agar came to England with his father in 1681. He primarily painted portraits on commission for patrons such as the Duke of Buccleuch and Lord Bolingbroke.[6] Some of his works can be found at Nunnington Hall.
The spelling d'Agar[1] is commonly present in bibliography including reference books.[2] Although, variant spellings are also known in 17th-century and 18th-century sources, such as Dagar,[3]de Garr,[4] and others.
Stein 1907, p.112, and Bénézit 2006, p.148, describe d'Agar as a French painter. Alternately, Marciari Alexander 2004, p.904, says that "[d'Agar's] œuvre was clearly of more consequence to English art than that of his father."
Vertue, George (1930). "The Note-Books of George Vertue Relating to Artists and Collections in England (I)". The Walpole Society. 18. p. 83, 116, 126–127. JSTORi40086539.
Vertue, George (1934). "The Note-Books of George Vertue Relating to Artists and Collections in England (III)". The Walpole Society. 22. p. 1, 4, 15. JSTORi40086509.
Whinney, Margaret; Millar, Oliver (1957). English Art, 1625–1714. Oxford History of English Art. Vol.8. Oxford: Clarendon Press. p.199. OCLC1150992276– via the Internet Archive.
Du Bus, Charles (1933). "Agar (Charles d')". In Balteau, Jules; Barroux, Marius; and Prevost, Michel (eds.). Dictionnaire de biographie française (in French). Vol.1. Paris: Letouzey et Ané. col. 685. OCLC492149976.