[user104658]

The obvious answer is that it's a bit of both? Yes further education is skewed towards younger generations but, also, people seem to be undervaluing the effect of having a higher level of education. One of the main ones is higher levels of critical reasoning skills; which means that "catchphrases" like "strong and stable" are less likely to work on (and are in fact likely to irritate) those who have been through the higher education system. May relied HEAVILY on these sorts of phrases and was very lazy about fleshing them out with any explanation. She just repeated them over and over like a dodgy Buzz Lightyear, trying to create an association. "The Tories are strong and stable and we need that! They must be, they keep saying it over and over."

Basically, the less educated you are, the more susceptible you are to basic advertising. Flat out fact.