I seem to recall one of the variant's in Avalon Hill's classic Third Reich boardgame to be, "More commitment from the Empire" for Britain. Now, in real history, what would this mean? The Aussies sticking around Europe instead of the Pacific? Or something more?
Would it have been possible to mobilize even more of the manpower and resources of India then was OTL? Could Canada have realized one of her occasional, almost secret ambitions and built a massive warfleet?
Or is all this half-baked?
Got to say this seems a bit of a strange idea; the committment from the empire was considerable and I am a little hard pushed to see how much more it could have done-many of the contributions are ignored esp the 'non-military' ones(such as Belizan woodcutters coming over to Scotland to work on the forestry estates, bands from the colonies coming over and performing in the UK, not to mention the amount of war bonds everyone at all levels in the colonies bought).
In a way, the change is not so much 'more committment from the empire' but 'British government making better use of the offers of support from the empire'. Two examples could be
Remove the relucance to accept colonial volunteers into the RAF, etc.
Make efforts to better equip imperial forces (for example I think the Indian Air Force didn't get Spitfires until 1945! Imagine a policy to give the Indian Air Force modern designs, locally produced, being enacted prior to 1939-perhaps a couple of squadrons of early Spitfires could have made a considerable difference to the early stages of the war in the Pacific)
The Greffrye Museum in London (near Elephant and Castle) currently has an exhibition on about the role of the London Carribean community in WW2, as part of the exhibition it has a lot of info on the war effort of the West Indies colonies, it was considerable-it wasn't always used to its best advantage