Sift the flour, sugar, salt, and baking powder together. Add the suet,
 chopped currants, and enough cold milk to make a soft but not sticky 
 dough. Shape into a roll. Lay the dough on a scalded, well-floured  
 pudding cloth and roll up loosely. Tie up the ends of the cloth. Put 
 into a  saucepan of fast-boiling water, reduce the heat, and simmer 
 for 2 to 2  1/2 hours. Drain well and unwrap. Slice and serve with 
 any custard or sweet  sauce, or with warmed golden syrup and cream.