Dubliners

When I was growing up, folk music was a bit of a joke. I mean, it was the sort of stuff that inspired the Vic Reeves spoof, where bearded men stroll about in tight nylon rollnecks which showed their nipples. There was a  bit of it on telly - the Spinners and Steeleye Span and what not, but it was noteworthy mainly for being hugely inoffensive and safe family viewing. When you recall that this was the era when Jim Davidson was on telly it makes you blench.
Then I discovered the Dubliners, and not the later incarnations but the Original Dubliners line-up of 1966-1974. Just a look at the album cover suggests they're a bit dangerous:

That dodgy-looking geezer second from right is Ronnie Drew and the wild-looking dude in the middle is Luke Kelly, and they were the heart of the group and sang many of the great songs. Then l-r John Sheahan, Ciaran Bourke and Barney McKenna. Hard-drinking, heavy-smoking legends. Bourke suffered a brain haemhorrage on stage in 1974; Kelly collapsed on stage because of a brain tumour in 1980; Drew died in 2008 of throat cancer - perhaps a million cigarettes are why his voice sounded "like coke being crushed under a door". Sheahan and McKenna are in the band to this day. In later years they started to self-censor a bit - the rebel songs like "The Old Alarm Clock" and "Rising of the Moon" largely disappeared from their roster, and for supposed reasons of decency you'll never heard all seven verses of "Seven Drunken Nights" on their albums.
But it's the Original Dubliners you want - the classic quintet - before the politics got in the way.