His grandson was Prime Minister Harold Macmillan .
Daniel Macmillan ( 1813 -- 1857 ) -- He and his brother Alexander founded Macmillan Publishers in 1843 .
Daniel Macmillan 's grandson was Prime Minister Harold Macmillan .
Daniel Macmillan ( 1813 -- 1857 ) -- He and his brother Alexander founded Macmillan Publishers in 1843 .