Cut the crusts off the bread and discard. Cut the bread into dainty sandwich-sized triangles or squares, or make small jam or honey sandwiches and put into a shallow dish.
Put the egg, and extra yolk if used, into a basin and beat well, beating in the milk, sherry or brandy, and sugar to taste. Pour in the egg mixture over the bread and leave for a few minutes to soak. Turn the bread over carefully and leave for a few more minutes until all the egg is soaked into the bread.
Heat the oil and butter in a large frying pan over a moderate heat until just hazing, and, using a fish slice, carefully put the soaked bread slices into the hot fat. Cook for a few moments until golden, then turn and cook the other side. Drain on kitchen paper and serve on a warm plate, dredged with the prepared sugar.