Robert was born in Saltcoats, Ayrshire (and had a twin brother, William Masters Sibthorpe Boyd). He married his first wife, Mary, in 1949 and had three children, Hazel, Robert and Stephen. She died in 1996 and, two years later, he married Betty.
His obituary in The Guardian is available here: Sir Robert Boyd, the father of space science in the UK
Robert's mother was Dorothy Jane Sibthorpe (a daughter of Willam Masters Sibthorpe). Robert's father was William J. Boyd whose sister, Janet Fullarton Boyd, married William "Ben" Earl Sibthorpe (a son of WMS). So Robert and William (and their younger sister, Joan) were first cousins of Elsie and Kathleen Sibthorpe (of Tunbridge Wells) on both their father and mother's side.
