“Och wise up!” chimes a female voice from a few rows back. Josh Rouse – smartly dressed in double denim and a dapper hat, gifted with a sweet, sleepy voice – has just announced that he is about to play his last song, and has been roundly chastised in the most affectionate way possible. The fact that the end of Rouse’s gig has been met with such a fine example of the Northern Irish vernacular should indicate how warmly his performance has been received. There is, to reach for that hoary cliché, a lot of love in the room –…