Thank you Cambridgelad.
That was from the 1923 Rose Annual p237, not 1943.
At the moment our records are showing:

DICKSON, A. (Alexander) (1801-1880 )
DICKSON, Hugh, (c1831-1904) son of Alexander I
DICKSON, George (1832-1914), son of Alexander I
DICKSON, Hugh II (1850-60s?-1922), son of Hugh
DICKSON, Alexander II (1857-1949), son of George, started 1872, retired 1930
DICKSON, George II, son of George
DICKSON, Alexander III (1893-1975), son of Alexander II, retired ca. 1958
DICKSON, Alexander Patrick (Patrick) (1926-2012), son of Alexander III
DICKSON, Colin, son of Patrick (1956-....). Ceased breeding in 2018.

I am having a problem with just who was “Sandy”. You have said
“According his grandson (Colin Dickson) his grandfather (Alexander Dickson III) was often refered to as "Sandy" within the famiy to save confussion with his father, Alexander Dickson II.”

And yet the 1923 Rose Annual article mentions “ at the National Shows, whilst his BROTHER, “Belmont Sandy,” was busy with the exhibition varieties, “Belmont Hugh” (terms used by exhibitors to distinguish them from their Newtownards relatives“ )