I'm surprised that the Mars company didn't cash in on their product's association (real or imagined) with Marianne Faithfull. In those days Cadbury's Flake (another UK choc bar) was advertised with a nubile person of the female gender eating the bar in a somewhat suggestive manner. Mars could have used Marianne in a similar way - obviously I mean eating it, not in any other improper way, which in those days would have been frowned upon by the ITV authorities.