I crossed Blackfriars Bridge this morning to see the exhibition of photographs by Jim Grover in the gallery on the ground floor of the Oxo Tower.   He has documented a year in the life of Kit Gunasekera, the vicar of St. James’s Church in Clapham, in black-and-white on a digital Leica camera.   What comes across is the toughness of the life of the clergy nowadays, administering to a shrinking and generally elderly congregation, documenting every service and the numbers attending.   It’s an effective piece of photo-realism, helped by the Sri Lankan saintliness of the clergyman’s face.