This was an extraordinary campaign led by the British Government; before WW2 , the government realised that the population would go hungry if the war was to last longer than a few months. The result was that formal gardens, lawns and even sports pitches were transformed into allotments, large and small, and everybody on the home front was encouraged to become a vegetable gardener.
Before World War II, Britain imported over 55 million tons of food a year – much of it from Canada and the USA. After the outbreak of war, merchant vessels carrying provisions into Britain, especially those coming across the Atlantic, became targets of the German navy and food imports were under threat. At the same time the British government recognised that the merchant ships were required for the transport of troops, munitions and even aeroplanes to the theatres of war. Our reliance on imported food needed to be reduced
In a well-publicised speech in late 1944, Lord Woolton said:
We can justly congratulate ourselves in what we have achieved. But we must on no account relax our efforts. The war is not yet won. Moreover, even it were to end in Europe sooner than we expect, the food situation, far from becoming easier, may well become more difficult owing to the urgent necessity of feeding the starving people of Europe. Indeed in many ways it would be true to say that our real tasks will only then begin. Carry on therefore with your good work. Do not rest on your spades, except for those brief periods which are every gardener’s privilege.
(Source: Hg2g Earth blog)