Early 1970s Safety ad, possibly.

[spillage66]

All I can remember is that a bloke and a woman are doing domestic stuff, and the man accidentally drinks the wrong glass of *milk* (maybe in the garage or shed)... and it ends up with a shadow of a monster, (Jeckyll & Hyde -esque) looming towards the old lass, and her saying, "Henry? HENRY!"
Anyone have the slightest recollection? It was either for milk, or just a generic safety advert thing for labeling stuff. (UK, early 1970s)