According to an interesting article I came across recently in The Guaradian: http://www.theguardian.com/media/2009/aug/10/longest-running-newspaper-ad this ad...View More
has been running for over 50 years with the text largely untouched (just headline changes). According to the article, they sold over 400,000 English courses. The first two ads below are versions of the campaign used in the 70s. Below those two ads are three ads that actually come from another company selling the same thing & using a very similar pitch. It's important to note that the second company ran the ad for over a decade in the 60s & 70s, specifically in minority publications such as Ebony, a magazine targeted at African Americans. If you think about it, at the time, there was more racial inequality/seperation & the idea that they could be confident in their English speaking abilities would seem to be pretty desirable and bring about feelings of fitting in more and feeling worthy and proud. As to why the ads did so well. I think it has largely to do with the niche and lack of substantial sophistication in the market. It's not a market full of hype, big claims & over-promising. It's very straight forward and more educational than most niches. There is always a need for people to learn English and many feel shame that they don't know it well, especially new citizens.