I find that very hard to believe. Reading through the cabinet papers there is never any great urgency in the food situation. Plenty of long term concern, but if stocks were so low at any point there'd have been dramatic cuts to rations etc. Most of the references to food during 1943 are either regarding the situation in India or about relief supplies for occupied Europe after the war.it does not counter the information that on one occaision the reserves of food supply in Brtain was down to three days.
The fifth report from the shipping committee, April 1943, has the following figures for food stocks (excluding farm and retail stocks):
Stocks at end of 1942: 5,644,000 tons
Home production: 10,598,000 tons
Arrivals from Eire: 96,000
Consumption Jan - June 1943: 15,806,000 tons (including air raid damage and expired food)
Stocks at end of June: 5,480,000
That shows there were just over 2 months of stocks at the end of 1942 and still just over 2 months in the middle of 1943. That doesn't rule out a collapse to 3 days at one point, but it does make it unlikely. I don't see how the storage and distribution system could function with only 3 day's supply, either.