In Hebburn, Leslie largely funded St. Andrew's Presbyterian Church, which opened in 1873, and built other buildings including homes for his workers, schools for their children.[2] He was married to Margaret Leslie.[2] Leslie also lived at Coxlodge Hall in Gosforth[6]
He died on 27 January 1894 aged 75. He is buried in a family plot at Rosebank Cemetery in Edinburgh,[7] against the west wall, near the north-west corner.