I didn't find Mokara Meda Arnold in the RHS registry but I did find
Ascocenda Meda Arnold = Ascocentrum curvifolium X Vanda Rothschildiana
and the only one I found was a cultivar that produces 'Red Scarlet' flowers -
Ascda. Meda Arnold 'Red Scarlet': Orchids By Hausermann
No where as beautiful as yours , Don
From the book - Na Okika O Hawaii =: Hawaii Orchid Journal
By Honolulu Orchid Society, Pacific Orchid Society, Pacific Orchid Society, Honolulu Orchid Society
Published by Honolulu Orchid Society and Pacific Orchid Society, 1975
Original from the University of California ;page 22.
"In 1949 Dr. Sideris flowered and registered Ascocenda Portia Doolittle, an intergeneric hybrid, which was followed by Ascda. Meda Arnold in 1950."
Perhaps there is a Mokara Meda Arnold