Our college choirmaster had a trick that he liked to deploy when he sensed that we were phoning it in. He ordered us out of the choirstalls and positioned us at random all over the chapel. It was sadistic but effective. With nowhere to hide, there could be no quiet fudging of that awkward leap in ‘O Thou the Central Orb’, and no waiting until after a more confident neighbour had begun their note before scooping hastily (and hopefully unnoticeably) upwards to match their pitch.