It appears from a Scotlandspeople search that he died in 2021 -
Statutory registers - Deaths - Search results | ScotlandsPeople
Can't immediately find a death notice/obit but it is getting late...
He was the son of Sir THomas INNES of Learney GCVO, Lord Lyon KIng of Arms (1893-1971), scion of the Baronets Innes of Balvenie being descended from Robert Innes of Innermarkie greatx2 uncle of the 1st Bt, and (m 1928) Lady Lucy BUCHAN (d 2012 aged 100) dau of the 18th Earl of Caithness. Acc to DPB he was unm