From the Telegraph:
http://announcements.telegraph.co.uk/deaths/119933/graham
GRAHAM Robin Angus, peacefully in his sleep on Sunday 1st August, beloved
husband of Clare, much loved father of Anna, Lorna, Polly and Robert,
and proud grandpa of Jack, Ruby and Kitty. A celebration of his life
will be held at St Peters Church, Seaview, IW, on Tuesday 10th August at
11.30 a.m. following a private family funeral. Donations, if desired,
to Cancer Research UK and all enquiries to [...]
Clearly resident on the Isle of Wight, which fits with the Winchester probate record.
I agree with Stephen that we are probably dealing with another Robin Angus GRAHAM in the 2010 death record. From the school details we would expect this man to be born 1943-1945, and indeed FreeBMD search brings up:
Q1 1944: GRAHAM, Robin A, mothers maiden name BRUCE, District WANDSWORTH.
A Robin A GRAHAM appears to marry a Felicity GROSS 1967 CUCKFIELD, and with her has dau Anna Felicity (1970) and Lorna Cecilia (1971).
There is then another Robin A GRAHAM marriage to Clare J C TAYLOR 1986 ISLE OF WIGHT and with her has dau Polly Elizabeth J (1988) and a possible Robert in Hammersmith in 1991.
I re-checked the Probate indices, there are no other Robin Angus GRAHAM records, so it is possible that the MONTROSE scion is still living. Having checked electoral roll records, he can be seen at Blaxhall, Woodbridge in 2003 and not later, but he may have taken himself off the public roll.