The phrase "late son" is correct and can be used in written English.
An example sentence might be: "My late son was a great source of inspiration to me."
He is predeceased by his late son, Louis R. Levin.
Loving mother of Bonnie and her dear late son, Steven.
The tradition of tikkun olam was shared with their children, including their late son, Steven.
Eleanor recognizes the resemblance between Philip and her late son King Richard Coeur-de-lion Coeur-de-lion Coeur-de-lion
Beloved wife of the late Paul Schwartz and mother of her late son Sing-Si Schwartz. Sing-Si Schwartz
Devoted mother to her late son George and daughter-in-law Honey.
It was all produced by her late son Terry Melcher in 2004.
Those who thought David Cameron understood disability because of his late son were very wrong.
COHART--Beatrice, 89, beloved wife of the late Henry, daughter Judith, late son Richard.
A faded colour photograph of her late son is pasted to the glass.
Ford mentioned his late son Tom in thanking his family, his voice clutched by emotion.
