I heard about him on a Channel 4 show ages ago,* but was on my way out so didn't do a lot, but the name stuck in my head after I was transfixed by what I saw. Folk music will never be the same again.
It's still on my to do list to get some Seth Lakeman stuff, but YouTube is sufficing at the moment.
*by 'ages' I mean 18months to two years ago, if not more, I can't remember (funny how names stick in your head though). This post may seem 'a little late to the party' but it's more about getting other people hearing his stuff. He only really came into the public eye after someone heard his work and nominated him for the Mercury Music Prize (or whatever name you know it under yada yada). That catapulted him into the mainstream but there are still not enough people who know and or appreciate Seth Lakeman, hence this post.