In case this family comes up again in future:
They were quite numerous and mainly connected with colonial administration, particularly in India. Tam Dalyell's father, (Percy) Gordon Loch, C.I.E., was John Hamish Carysfort Loch's second cousin twice removed.
Since the Loch/ Proby marriages occurred after the pedigree above was produced (the marriages are given in pedigrees of the Earls of Carysfort, however) here is an outline:
John Hamish Carysfort Loch was son of Laurence John Carysfort Loch (1901-) Maj. (hon. Col. 1948, post-retirement) Indian Army; I haven't managed to locate a marriage for him, implying it wasn't in England(?). L. J. C. Loch was son of John Carysfort Loch (1877-), sometime of Madras, India, and his wife (m. 1901, Calcutta) Violet Frances Jones; his father was John Lowis Loch (1839-), Capt. 2nd Bengal Light Infantry, son of George Loch by his first wife (m. 1835, Calcutta) Louisa Gordon. George Loch married secondly, in 1850, Lydia Augusta Proby, elder sister of John Lowis Loch's wife Lucy Harriette Proby. Both were daughters of Rev. John Carysfort Proby, rector of St Peter's, Cheesehill, Winchester. His father, Rev. Baptist John Proby, vicar of St Mary's, Lichfield, was nephew of John Proby, created Baron Carysfort in 1752, whose son John Joshua Proby was created Earl of Carysfort in 1789.