The government’s bread campaign – Don’t waste bread! – was a plea to make the best use of the staple food in a bid to beat the U-boat threat. At the start of the war, Britain was importing 70% of its grains by ship but this proved vulnerable to U-boat attacks.
In response, the government launched the campaign and devised the National wheatmeal flour, characterised by a high extraction rate, allowing more flour to go around, and a higher fibre content.
The resulting National loaf was government regulated and sold nationwide from 1942.