The late Mrs Scott's paternal grandparents were Capt Gray Kynoch Leathart ("Bino") RAE (28 IV 1887 - 28 II 1947) and his wife (married 1916), Elsie CHAMPION (20 VII 1896 - 4 VII 1955). Capt Bino Rae was the third son of Edward RAE, FRGS (20 III 1847 - 26 VI 1923) and his wife (married 1882), Margaret LEATHART (1862 - 1 V 1936). Edward Rae was himself the younger son of the noted banker and art collector, George RAE (21 X 1817 - 4 VIII 1902) and his first wife (married 13 III 1845), Elspeth KYNOCH (died 10 III 1851).
The birth of a George John FRERE-SCOTT was registered in Galashiels in 2020 (ref 810 / 52) and the birth of a Robert Christopher FRERE-SCOTT was registered in Melrose in 2021 (ref 820 / 2); presumably, these are the sons of Alexander Frere-Scott and his wife, but, as Scotland's People does not give the mother's maiden name, I cannot be sure.
The birth of a William Douglas FRERE-SCOTT was registered in Wandsworth in Q3 2018, and the birth of a Clementine Rose FRERE-SCOTT (mother's maiden surname Pearson) was registered in Wandsworth in Q4 2017. As Jamie Frere-Scott and his wife appear to be resident in Wandsworth, it seems likely that these are their children, although the mother's maiden name did not display against the entry for William Douglas Frere-Scott when I looked on the GRO index.
Mrs Lucinda Christine Frere-Scott is the daughter of Capt Nigel John PEARSON, RN (1947 - [18 IX?] 2001) and his wife (married 1980, as her second husband), Thérèse Annabella ("Tess") HARDEN (born 14 IX 1949), who is herself the elder daughter of Maj James Richard Edwards HARDEN, OBE, DSO, MC (12 XII 1916 - 22 X 2000), MP (Ulster Unionist) for Armagh, 1948-54, and his wife (married 27 VII 1948), Ursula Joyce STRUTT (17 IV 1917 - 31 I 2007), a great-granddaughter of the 2nd Baron Rayleigh.
I cannot be sure, but Capt Nigel Pearson would appear to have been the son of John F PEARSON and his wife (married 1943, as her second husband), Christine Elizabeth CAVE-BROWNE-CAVE, née BENTLEY (16 VII 1914 - 24 III 1982). The then Christine Bentley's first husband (married 18 IV 1936, divorced 1943) was Myles Verney CAVE-BROWNE-CAVE (18 VII 1910 - ?), who changed his name to Glenn Myles LEVERING in 1944, and was a great-great-grandson of Sir William CAVE-BROWNE-CAVE, 9th Bt (19 II 1765 - 24 VIII 1838).