@shri I don't want to derail this thread as others have been, BUT:
The statements of world leaders who were under duress or playing politics with bias and agendas, - the statements of the enemy no less - does not necessarily reflect the reality of events. The likes of Foreign Minister Taleyrand couldn't have had it more wrong. The British have always relied on allies - but they have also always assisted them where ever possible and had their own navies and/armies operating aggressively.
The following figures are based on accounts I have read and am attempting to recall. Other sources might give slightly different figures - and I am not perfect - I may not be able to remember it all properly. So apologies in advance for any mistakes.
Now, as I understand it...
White Dominions were of limited use since they were often semi-independent, with control of their own forces needed to defend their own dominions. What was loaned was useful, sometimes decisive, and welcome, but usually not very sizeable in the scale of world war two. A similar problem lay with the rest of the empire, with British forces being spread thin to garrison and (try to ) protect it. Perhaps most importantly of all, just twenty years before, WWI had wiped out almost an entire generation, and so large had the call up been that war production in Britain had been left without enough workforce, so that war production had been compromised. Britain was intent on this slaughter and shortfall not happening again. So it took measures to prevent it.
The Military Training Act of April 1939 required that all British men aged 20 and 21 - no other ages - who were fit and able, were required to take military training. Even so, when war broke out the process had barely begun and the British Army could still only muster about 900,000 men
Recognising the need for more, Parliament brought in the National Service Act. This made all able men between the ages of 18 and 41 liable for conscription; (still no one younger than 18 note), with a priority on single men being called up before married men. To prevent a repeat of WWI the call up would be done incrementally. Furthermore, 5 million men were kept in "Reserved Occupations", necessary to keep the war effort going and the country itself running effectively. To fill the gaps left by those going to armed forces, women worked in factories, or on the farms (the Land Army) and filled many military non-combat support roles in the Auxiliary Territorial Service.
The age group included in the call ups gradually became more inclusive until by 1942 all healthy and fit males between 18 and 51 years old and all healthy and fit single and childless females 20 to 30 years old were liable to be called up. Unfortunately it is very difficult to ascertain how many eligible combatants this actually was - since many of the relevant records from the national census were lost or/and destroyed. However, of an estimated population of around 47 - 48 million (not 50 million), the children numbered about 14 million. Take out the other exemptions from service - women who were married, or had children, or who were older than 30; males older than 51; those deemed unfit for service; the blind and mentally ill; the Clergy, those millions in "reserved occupations" - it quickly becomes apparent that well over half of the population would not have been eligible for service in the armed forces - although many did their part on the Home Front. Several million kept the wheels of war turning, volunteering to be ARPs, Special Constables, Fire-fighters or Home Guard. Just a little less than half a million women joined the military and 6.5 million more had filled the jobs left empty by men, doing the same jobs men had (this of course suggests that at least 6.5 million men did mobilise, but the figure could be misleading, as war time production was far more intensive than at peacetime).
I have been trying to find the actual number of males aged between 18 and 51 and single women aged between 20 and 30 eligible for service - but such a figure appears to be lost. I have figures for the late 19th Century and pre WW1 - but obviously these are of little use. But even then, before WWI had taken so many, the number of men aged 18- 51 had only been roughly around 10 million. By 1939, after as many as 800,000 to a million people had died in WWI, and a further 250,000 had been lost to the influenza pandemic of 1919, the eligible manpower could not have been greater than 9 million at the very most. All I know is that by the end of the war 3.5 million had served in the British army (peaking at a maximum strength of 2.5 million), while about 900,000 served in the Royal Navy and 1 million in the RAF (with a further 200,000 from the Dominions and other allies). Tens of thousands had served in intelligence or covert operations. About 50,000 in the Merchant Navy. 37,000 more were sent to mines instead of the Front. I estimate about 6 million served (?). This seemed to push Britain to it's limit.
Since Britain was all about giving it's all ( bankrupting itself to keep the war going is not something you do if you are "holding back") and since in 1945 the army no longer had enough manpower and had to merge units to keep divisions at effective fighting strength, I would suggest that Britain did not have much more eligible man(woman) power (that it could afford) to use. The Army would not have left it's divisions short by choice, which rather implies that there wasn't much left in the eligible manpower reserves by 1945 - or/and that it did not have the funds to raise more. Either way, it rather seems that Britain had given it's all in the conditions it was operating under.
Regarding the Soviet Union: taking into account that Britain was giving it's all, and that Churchill knew full well that his country did not have the strength to take on Stalin, those "secret percentage deals" can be seen as nothing more than the realistic acknowledgement of the strategic situation, with Churchill, lacking any military clout and fast losing political influence too, still trying to save eastern Europe from complete Soviet take over. Churchill was always the first to fear and suspect the Soviets and he did not make that accord lightly - but since Stalin was not about to just leave -that had already been made clear - and since Churchill could not force him to militarily, a political compromise - and the hope that Stalin would abide by it - was all he could do.
And how is it "secret" if Churchill himself openly wrote about it in his own works?!
Regarding giving supplies and helping the Soviet Union: The UK got more aid - but then the UK was a lot easier and safer to reach!("Safe", being a relative term of course - the Atlantic was no pleasure cruise). However, despite the high peril 1400 vessels were still used in Arctic Convoys to try to get through to the USSR to give them aid from the US and Britain -supplies, arms, armour, aircraft - much of which Britain itself needed rather badly itself. These convoys tied up German forces that could otherwise have been used against the USSR and that instead sunk British vessels. Of the British ships involved, 16 Royal navy ships and 85 Merchant vessels were lost. The RAF lost lives too: Over 8,000 aircraft were lost in action. Bomber Command suffered over 55,000 killed - from a total of about 125,000. That's roughly around a 40% mortality rate. They died bombing the factories that were making the parts that made the arms and the planes and the tanks - disrupting, delaying, damaging and even destroying the production of German materiel, much of which would have been sent to the eastern front.
Many tens of thousands of British died trying to help the USSR, even if they didn't actually die side by side on the eastern front. That large chip on your shoulder? Take it off.
