The problem of providing beer for troops overseas

Learning new stuff. It's the main resaon I do all my research. I'm always happy to be pointed at something I'd never contemplated.

In this case, it's about all the beer shipped to the British troops serving abroad. Well, not so much the beer, as the bottles, crates and barrels in which it was packaged. It shouldn't come a surprise that virtually none of the packaging was returned. Which was a big problem during the war and its immediate aftermath as they could not easily be replaced.

The head of the off-licence trade organisation was very aware of this problem and made an appeal to the public in this letter:

"Christmas Beer
Sir —Despite acute shortages of hops, barley, labour and transport, the brewing industry is doing its best to provide Christmas beer for the public and our troops overseas.

Of the millions of beer bottles sent overseas very few return, and the consequent strain on supplies for home distribution is enormous. Brewers, licensees and off-licence holders will be faced with a breakdown in the bottled beer supply over the festive season unless they have the wholehearted co-operation of the public in returning all empty bottles, complete with stoppers, whatever their condition and wherever they may be unearthed.

May I, therefore, appeal to every beer consumer to search his cupboards and deliver to his "local” or off-licence every bottle he can find, and to renew the effort after the holiday.—Yours etc.
GEO BIRMINGHAM,
Secretary, National Federation of Off-licence Holders’ Association."
Birmingham Daily Gazette - Monday 17 December 1945, page 2.

Here are UK wartime exports by destination:

UK beer exports by destination 1939 - 1945
Destination	1939	1940	1941	1942	1943	1944	1945
Egypt	26,597	28,857	28,519	3,658	45	4,804	2,966
Irish Free State	52,081	35,306	25,843	16,730	14,810	4,878	128
British W. Africa	12,468	13,873	22,328	15,544	19,161	10,225	1,190
India & Straits Settlements	63,186	69,963	62,260	11,523	638	2,506	38,333
Brit. West India	10,925	8,499	8,081	5,082	6,629	1,701	7
Belgium	29,140	13,080
Other Countries	89,577	97,188	78,521	42,259	65,736	53,483	78,732
Total	283,974	266,766	225,552	94,796	107,019	77,597	130,443
Source:
Brewers' Almanack 1955, page 57.

Why the big fall in 1942? Could it be connected with the USA's entry into the war?