ah, session etiquette. it's a tricksy beast. not all sessions have an etiquette whereby you are treading on toes if you start a tune or song without being asked... some session leaders expect that their job is to just gently keep things going - by starting things themselves or encouraging the people around them to do so if there are gaps but otherwise by just being there. and that might seem like they're favouring their mates.

yep, you'd hope that people would be welcoming. But one person's idea of welcoming can be another person's idea of overbearing. I know people who don't like going to sessions where they get 'put on the spot' by a gentle invitation to do a song, because it makes them feel under pressure to perform whereas they just want to join in at the back and only start something once in a blue moon in their own time.

that said, I wasn't there, so maybe the sheffeidl survivors was one of the unfortunate cases where it's a closed clique...

a suggestion though, if you find that sort of thing happens at another session you're at in future. Just quietly & friendlily (is that a word?) ask 'what's the etiquette here - do I just start tunes or wait to be asked or what?' and 99 times out 100 that'll help the leader and any others there realise that you're not feeling sure about whether you're welcome or not...