Back in the 60's and 70's "folk music" was frequently in the charts and thus got plenty of exposure in the UK both on radio and TV:
Julie Felix on Frost and later with her own TV series
The Spinners with a TV series
Joan Baez in the charts
Chris Christopherson
Gordon Lightfoot
The Strawbs
Fairport Convention
The Dubliners
These are just off the top of my head without researching the subject.
An eclectic mix of contemporary and traditional Folk.
The music was very much in the public eye during this period and other modern media forms were not available - the transition from 78 to 46 records had only just occurred (my first record by Elvis was on a 78)
During this same time period tertiary education leapt from 3.4% to 8.4% from 1950 to 1970. These numbers also aided the growth of college folk. The same is not true for the explosive growth in higher education numbers post 2000.
But it must be remembered that society has changed over the last 50 years as have entertainment mediums. The state of the music is a very different beast to the state of the clubs, yet the two seem to be treated as the same by a minority posting here. As has been stated, a person can be a closet folk aficionado and no one would be any the wiser. Therefore there is no way of counting them. If those with a heavy involvement say the scene is healthy who are we to argue. This is a subject where google can give conflicting answers.