The suet needs to be minced or shredded finely, or you’ll get somewhat lumpy pastry.
Suet crust pastry may be the only pastry that needs a chemical rising agent in it. In most other pastries, the rising agent is steam within the pastry, but in a steamed pudding, the external steam would stop the pastry from rising.
The flour used can be white or wholewheat (aka wholemeal.)
You can also use suet crust pastry for baked items.
2 cups (10 oz / 300 g) flour
1/2 cup (2 oz / 50 g) of shredded suet
1 tablespoon baking powder
pinch of salt
Put flour, baking powder, and salt into a bowl, and stir them around with a fork (or put them all into a flour sifter, and sift into the bowl.)
Add enough cold water, a bit at a time, to bind it.
It does not need any resting time in the fridge.
Use about 3/4 of the pastry dough to line the pudding dish, and save 1/4 for the top.
Roll the two balls out in those proportions in rounds on a floured surface, and apply to your pudding dish.