This is such a useful skill to master. The pastry must have been chilled for at least half an hour and the surface must be clean and dry. Sprinkle the worktop with a small amount of flour (too much will dry the pastry out) and roll the ball of pastry around in the flour. Start to roll away from you with even pressure, and after each roll turn the pastry over (add a little more flour if it’s sticking to the worktop) and a quarter turn to the left or right. That way you should end up with a nice even circle about the thickness of a £1. Remember you can only really get away with rolling out pastry twice, after that it gets a bit tough and leathery.