If it helps, the link on the parody dates it 1978, with the original ad being 1973.

Note the controversy in the parody's comments section about the setting of the original ad. One commenter knows that it was filmed in Dorset but says it's set in Yorkshire. Reply says: no it isn't. First commenter rebuts by stating it has a Yorkshire-accent voiceover. Reply says: no it doesn't.

So here's another case of someone so sure it's Yorkshire that they misremember the accent.