Six recent stories--three of them first-rate. In ""Cocky Olly,"" a young girl at the turn of the century not only has an education in British bohemia but finds herself actually enrolled in a pointless adventure along with a schoolmate--a train trip that is a child's desperate attempt at flight. What's so consistently fine about Pritchett the story-writer is his eschewal of conventional psychology in favor of the headlong: if he knows anything about narrative, it is its simmering drive. Train rides figure prominently in other stories too, for they allow dream and insight to coexist (""He had looked out the window of the train, once just in time to catch sight of a wide estuary where the sailing boats were moored, and in that glimpse of the sea he saw it had lost its air of heaving and grieving at its stored up-deaths, it was waving like a flag""). More stationary is ""A Change of Policy""--a love-affair that institutes itself out of sheer surprise and unlikelihood. Pritchett's emotional ecumenism--neither pessimist nor optimist, he--is always a draw in his prose, be it fiction or criticism, and here remains so too.