A giant dove is flapping its chalky wings lugubriously across the cathedral rafters, moving slowly and deliberately towards the Great West Door. Its flight signals promise: there is more, much more, ahead. Suddenly the nave is flooded with the rays of a yellow sun; and then a giant mosaic, shards of light from a huge stained glass window, seeps into view.

This is Lichfield Cathedral, a lesser-known jewel in Britain’s ecclesiastical crown, but not as anyone has seen it before.