There's three of them across the table from me, young women in their distinctive Woodford House blazers, lapels twinkling with the multicoloured metallic souvenirs of busy and varied lives. They check that their phones are set to silent - these are Millennials and polite ones - and look at me with a kind of open and expectant curiosity. I don't think they have had a conversation with a bishop before, but they aren't particularly fazed. They share their names and a little of where they're from and a little more about where they hope to be next year. The ambition is impressive. "Tell me," I ask the one nearest me, "what exactly is a Service Prefect?" She looks at me steadily and smiles. "Excellent question," she replies. "I asked myself that exact same thing at the end of last year when Mrs Peterson invited me to do the job." And then she tells me what she has decided. About the working out of the school's Christian foun...