A probate search reveals that he died on 8 June 2023, probate granted 1 February 2024.
(This information has been taken from my working notes from DPB online which I have not been able to verify). He was b 1932 (when his father was about 17) the natural son of Winston Hillier Gopal ONSLOW (1915-1999) scion of the Earls of Onslow, though only in remainder to the Barony of Onslow (by special remainder) and the 1674 Baronetcy, being descended from a brother of the 1st Baron, and Dorothy Maude SHAKESPEARE later ONSLOW. He m 1965 (DPB says 1964) Gillian Ann ALLDER (1943-2022) and had 2 s and 2 d.
The recording of the funeral of his w Gillian is available on YouTube. It can been seen from the tributes that the late Mr Onslow was known as "Alan". His elder son Lynden is resident in NZ and his yr d Linnet has m Chris. In her tribute LInnet states that her parents married on 3 Oct 1965.