To make sense of this claim, we need to clear as to what the role of Britain's powerful wartime Ministry of Supply actually was.
The Ministry of Supply (the MoS) was never the British equivalent of the American War Production Board (WPB), no matter how many times this claim is offered up.
In fact, it was very much closer in spirit to Vannevar Bush's powerful Office of Scientific Research and Development (the OSRD) per the role set out for both under statute , than it was to the statutory role set out for the WPB.
Britain's Ministry of Supply strived to supply the military's needs - period. Unlike the WPB, it did not try to arbitrate between the conflicting demands of civilian and military claims upon scarce material and manpower.
Equally, the OSRD did NOT deal with all of America's wartime science and research efforts , a point that no doubt Jesus Christ himself will have to repeat again and again to academics on Judgement Day and on into all Eternity.
It only dealt with that amount of science and research that involved the designing of (but not the production of) new weapons that could come into use, during the current war.
Bush was very very careful to sharply limit the parameters of his organization, all to make it more dominant within its narrow but vital sphere.
So when Howard Florey went to both the OSRD and to the Ministry of Supply to help in the production of penicillin - rather than going instead to ask help from the American Public Health Service and the British Ministry of Health, he had already made it very clear where his penicillin priority lay.
He wanted additional penicillin production yes --- but only sufficient to supply the armed forces, period.
Florey was strongly conservative, as were all the key individuals within the Minister of Supply and the OSRD : Big Government to them was abhorrent.
Thus the sudden willingness, eagerness even, of the Ministry of Supply in the Fall of 1942 to go all out and seize control of all of the British commercial penicillin production has to be seen as ideologically surprising.
Unless it can (and should) be seen as the opening conservative counter-attack against the rumoured radical notions of the Beveridge Report.
A preemptive move to ensure that the Ministry of Health (also run by a Tory minister but with wider than just military responsibilities) didn't dominate penicillin production.
If is often claimed that the Ministry of Supply took over all of penicillin production because the Scottish-born minister was an old pal of fellow Scot, Alec Fleming, who asked him to do so.
Politicians - grant us at least this - do not spontaneously fall upon old friends and their requests with open arms --- not unless it suits us.
In September and October 1942, Fleming's request much suited Duncan and the British Tories.
In late September and October 1942, the tenor of the Beveridge report, though as yet unreleased, was well known within the top officials of Whitehall.
It called for a placing the values of equality and egalitarianism at the core of the British government - a notion intensely hostile to Tory values.
For penicillin, all this Beveridge "equality" talk could only mean one of two things.
It might mean divvying inadequate amounts of penicillin equally between dying civilians and dying soldiers - when Tories felt the most vital hope of penicillin was that it would help maintain current front line troop levels without the need to "call up" middle class men (their voters) now at home engaged in war work.
Or it might mean diverting the cost of one additional Lancaster squadron (three million pounds) away from the all-out bombing of civilian Germany , towards creating more penicillin factories on the successful Glaxo model.
Glaxo had taken up space in bits of idle factories and by using local cheap and plentiful unskilled labour,( aka women) , had cheaply but efficiently produced a lot of penicillin with current low technology methods and equipment.
(Basically making penicillin as if it was a milk product , using the very abundant modern dairy equipment existing everywhere thanks to the 1920s civilized world's mania over pure milk.)
A lot of similar factories could be quickly brought up to speed, supplying a good deal of penicillin, without requiring too much vital material like stainless steel, already in desperately short supply.
If all this sounds very familiar, that is because this solution is what Britain in the end was forced to do - but very late and only under intense public pressure.
If it had been done wholeheartedly in the Fall of 1942, there would have been no highly public late 1944 civilian penicillin famine crisis.
But the Conservative bits and bob of the Coalition Government wanted no part of equality and penicillin was just the first of many counterattacks against the threat of Beveridge.
They were unsuccessful in the extreme, blowing what had to seem to them (and to Labour !), a sure electoral victory at war's end.
"Unfair distribution of a vital commodity in short supply" , to quote The Times (of all people !) referencing an earlier debate over Hugh Dalton's fuel rationing proposals , was totally anathema to the British public.
In June 1945, what little polling type information we have suggests it was the unfair rationing of medical services that moved people to Labour .
The most current example of that unfair medical rationing had to be rationing difficulties with life saving penicillin.
Let me repeat that : "life saving". This was not just temporary unfairness in allocating housing or clothing : this was the unfair allocation of life itself.
You can't get a more "vital commodity" than life itself : to switch from the specialized language of the economist to that of the political scientist trying to account for a surprise pattern of vote changing, "life" is a very salient issue.
If so, the unexpected and total defeat of Churchill's Tories in June 1945 can be seen as having its origins in the Fall of 1942, when the Ministry of Supply (and Howard Florey) successfully re-defined the shortage of penicillin (contra Beveridge), as a shortage of military penicillin, civilians be damned.....