Put the treacle into a small bowl, add the boiling water, stir to dissolve and set aside.
Measure the milk into a jug, stir in the vinegar, cover and leave for 30 minutes.
Rub some oil around the inside of a 1kg/2lb loaf tin and pre-heat the oven.
Put the plain white and wholemeal flours, bicarbonate of soda and salt into a bowl and stir to combine.
Sieve the flour blend into a mixing bowl adding any bran left in the sieve.
Add the watery treacle mixture to the prepared milk, stir and pour everything into the mixing bowl.
Stir to make a slightly sticky dough.
Tip the dough into the prepared loaf tin, smooth the top and sprinkle with a little flour.
Bake for 40-45 minutes.
Allow to cool completely before slicing.
