He disappeared and never came back (I'm guessing since he was most likely a fraud).
But in Season 4, when the family is visited by the American in-laws, listen to the voice of the character, the American valet, who recruits the kitchen cook. He sounds just like Patrick Gordon's character.
Different actor I'm afraid, and Gordon's burns were so bad they could not be covered up with plastic surgery so well. Plus, Gordon was not American; he was serving in Canadian forces.
That was an erroneous choice on someone's part. The actual Patrick Gordon was a British friend of the dead Patrick who later went to work in Montreal. He would have had a upper middle British accent, though perhaps softened by a few years' residence in Canada.
He didn't even have the right Ontario accent. The Canadian Anglophile upper crust then and often now have something called an Upper Canada College accent, from the exclusive prep school. Peter Jennings and Christopher Plummer speak that way. Patrick Gordon had a modern middle class accent.
What do you think?