A tree on Ancestry has his death as 25th January 1951, in Sloan Street, Leith, widower of Margaret Jane Smart, and has a copy of the registration.
Death of Margaret shown as 1947 in Leith.
Three children:-
Winifred Annie 1911 Edinburgh, married James Thomas Lawrence, b 1907.
John 1916-1995 Edinburgh, no spouse named
David Smart Whitfield 1920-2002 Edinburgh, married Helen Innes Telfer, 1925-2009.
Two unnamed children of David
It also has a record of another daughter, Stella Murdoch Bagier, on 13th July 1921. Parents shown as John William Whitfield and Magdalene McDonald Bagier, nee Murdoch.
The registration gives her mother as widow of Thomas Bagier, killed in action in 1916. Stella's marriage gives her father as Thomas Bagier.