No doubt about it, as one Lent succeeds another, the BBC Radio 4 talks commissioned to mark the seasongrow steadily more oblique. This year’s theme is “performance” and both of the first two speakers, James Runcie and Kate Saunders (25 February and 4 March, respectively), were keen to establish connections between the practice of Christianity and their own professional careers. This was less self-aggrandising than it sounds, because Runcie, as well as being the son of a former Anglican archbishop, is the author of a series of detective novels featuring an Anglican vicar. The fervently Anglo-Catholic Saunders, on the other hand, is a former actor for whom the Mass is, naturally, the greatest show on earth.Runcie described his sequence of “Grantchester mysteries&rdqu