Because bread was so important, the laws governing its purity were strict and the punishment severe. A baker who cheated his customers could be fined £10 per loaf sold, or made to do a month's hard labor in prison. For a time, transportation to Australia was seriously considered for malfeasant bakers. This was a matter of real concern for bakers because every loaf of bread loses weight in baking through evaporation, so it is easy to blunder accidentally. For that reason, bakers sometimes provided a little extra- the famous baker's dozen.
Bill Bryson