A while back when we still had a tradition and not a revival, sessions took place in homes, pubs and all sorts of other places. They also included people who would (step) dance, tell stories, sing and play. I'd be interested if anyone knows where the first two still take place. Singing in sessions seems to be on the decline unless you know plenty of lusty chorus songs or unless you go to a directed (led) session. I understand that beginners, novices and strangers can upset a session, but who is going to be the arbiter of who should practice a bit longer in the bedroom? Sessions are a good way to discover style or a new tune. The sensitive novice will hold back or play quietly, the sensitive master won't hijack someone else's contribution.

With respect to keys etc. tunes tend to be played in the keys which suit the instrument and player. So for a fiddle, mandolin, Anglo concertina and melodeon, expect D and G to predominate, guitarists will use a capo if need be or the more adventurous will start to use alternate tunings (like the aformentioned Carthy and Simpson who care more about helping and encouraging rather than criticising and patronising). Singers will pitch to suit their voice and surroundings. So the notion of a particular key for a trad song or tune is false. They may have been collected and notated by people like Sharp in a particular key, maybe the key that the source used, maybe a key the collector favoured, but a virtual stave for the notation would be more appropriate (ie you can shift the root up or down to suit which key you like). Without notation, much of our tradition would have been lost, so don't knock it. If morris dances could have been notated easily, then Sharp would have preserved these along with the tunes. There are plenty of morris tunes archived now which have lost their dances forever.

The beauty of folk music is that it is something that can be experienced by all who want to participate and that's they way the traditionalists rather than revivalists saw it. It was something to share and celebrate. The only other genre that springs to mind that matches that is pop karaoke.