Have finally found what I think are the original grant loaf ingredients, of course it's imperial! And I haven't tried it.
The grant loaf
To produce three of these loaves required 3 lb. of stone-ground whole-wheat flour; two pints of water; two teaspoons of salt; three teaspoons of Barbados sugar (or, alternatively, a tablespoonful of honey); and three teaspoon measures of dried yeast.