Preheat oven to 190C, 170 fan, gas 5.
Sift the flour and salt into a large bowl.
Add the butter, cut up into small pieces. Rub the fat into the flour with your fingertips until the mixture resembles breadcrumbs.
Add sufficient water to bind mixture into a stiff dough.
Knead lightly on a floured surface. Roll out and use as required.
Roll large enough to cover a 25cm pie plate, keeping any leftovers to make a trellis.
Cover and place in the refrigerator to relax the pastry and help prevent shrinkage, while preparing the filling.
For the filling, melt the butter and golden syrup together.
Stir in the breadcrumbs, lemon juice and zest.
Spoon filling into the pastry case, decorate with strips of pastry to form a trellis.
Bake for 30 minutes until the pastry is golden. Dust with icing sugar and serve.