If the second half of the 20th century saw opera throttled by existential crises, and left composers wondering whether the only future for the art form was for it to be hung out to dry, or to become an arcane intellectualised annex for the musical games then in vogue, Gerald Barry's one-act opera, La plus forte (2006) - receiving its UK premiere in a concert performance last night - marks the end of hostilities. So effortlessly does Barry seem to rise above the tangled, stagnant realities of recent operatic and musical convention, and return and restore the art form to the business of psychological entrapment, that it's hard not to see his small, 20-minute work as one of the most significant operas of the past decade.