We need to remember that often the audience is the rest of the pub - its regulars who may feel we have highjacked their space. ( + bar staff ).
With a singing morris side ( one that gets invited back each year more because of the pub entertainment rather than the dancing ) then you can not afford too many singers who are average at best or those tunes/songs in non melodeon keys that others find difficult to join in with. Nor do you want wall to wall melodeon tunes in those minor keys.
Jolly tunes, songs that non folk people know with join in bits for other singers and musicians, and funny songs seem to work best. Follow an average performance with a better one if possible. Make sure the last 15 minutes is guarenteed good - even if it means going out of order on a sing around.
Then you get invited back.
FloraG