He married Judith Lawrence, the daughter of Thomas Lawrence, at St George the Martyr, Southwark in 1763. He was in partnership with Thomas Lawrence junior (Grimwade p.577) as watch case makers from 1771. Judith’s christening record at St Giles, Cripplegate in 1743 shows her father as Thomas Lawrence watch case maker (Grimwade p.577) and her mother as Judith.
Four children of James and Judith Sage were christened at St James, Clerkenwell from 1773-79.
In 1780-81 he was assessed to Land Tax at Clerkenwell Green. A new tenant was assessed in 1782.
Judith Sage aged 37 years, late of Clerkenwell Green, was buried at St James, Clerkenwell in 1781.
The burial in 1785 of a James Sage aged 43 years, late of the Workhouse, registered at St James, Clerkenwell may be relevant.