Mr Proctor, 65, was last seen at around 11.15am on Tuesday, July 6, and concerns are growing for his safety as it is thought that he may have travelled to Ayrshire.
He is roughly 6ft tall and was last seen wearing a lilac polo shirt, blue jumper and cream shorts.
Constable Laura Kelly, of Giffnock Police Station, said: "We are growing increasingly concerned for Gordon's welfare and appeal for anyone with information, or Gordon himself, to get in touch with Police Scotland on 101 quoting incident number 2460 of July 6 2021.”
Police Scotland has Missing Person Coordinators (MPCs) in every local division in the country.
MPCs support and oversee all missing person investigations.
Police Scotland says MPCs ensure missing persons have the “correct level of support” once they are found.