Roll out half the pastry on a lightly floured surface and trim to a 30 x 18 cm (12 x 7 inch) rectangle. Transfer to a lightly oiled baking sheet.
Pile the peach or nectarine slices on top, leaving a 2.5 cm (1 inch) border of pastry showing, then sprinkle on the blueberries, sugar and lemon rind. Brush the pastry border with a little beaten egg.
Roll out the remaining pastry to a little larger than the first piece, then trim to 33 x 20 cm (13 x 8 inches). Fold in half lengthways, then make cuts in from the fold about 1 cm (½ inch) apart and about 6 cm (2½ inches) long, leaving a wide uncut border of pastry.
Lift the pastry over the fruit, unfold so that the fruit and bottom layer of pastry are completely covered, then press the pastry edges together. Trim if needed. Knock up the edges with a knife, then flute (see
Brush the top of the pastry with beaten egg, sprinkle with a little extra sugar and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 20–25 minutes until the pastry is well risen and golden brown. Dust with icing sugar and serve cut into squares, warm or cold, with cream or ice cream.