You bring up a good point. I also play pubs (I'm in the United States) and while I must do the 'expected' pub songs, I weave traditional music into my repertoire. This is especially possible during the quieter times. For several years, I played at a pub on Sunday evenings. Little by little I introduced traditional ballads, usually telling the story before I sang the song. The audience got drawn in, and after a while we had a regular little Sunday group of people who came to hear the traditional stuff and would request it. I must agree with Tony - if you only do folk music in 'folk' venues you won't get any new people interested in the real thing.