I have been reading online about it. But everything just goes over to the UK borrowing from the US. Which isn't really the part I'm trying to learn, or at least, it's missing the other half.
It says in some places that Britain largely funded the other allies throughout the war, but after 1916 it had to be done through heavy borrowing.
Then the final question, how much did Russia leaving the war cost Britain, as they no longer paid there debts, I have seen in some places, that allies being unable to pay, or just refusing to, is what lead to the UK suffering so badly in the post war world.
How true are these? And what more is there to know?
A great reference is Adam Tooze's Deluge, which goes into the financing in some detail.
New York banks with strong ties to London helped the British raise debt. This was not a big issue until around 1916 when the British ran low on gold and foreign exchange. Income tax and war bonds were introduced to support further borrowing.
There were political factions, especially isolationist Republicans, who tried to prevent the raising of such debt as they saw it as both a violation of neutrality, and as dragging the US into the war. This tension between anti-war legislators, legislators in favour of supporting Britain, and bankers, was great.
With the entry of the US into the war, loans to all the Allies were effectively guaranteed by London. This meant US money guaranteed by Britain was used to place contracts in French factories. This integration of Allied financial and industrial power, although not perfectly efficient, was one of the little-recognised achievements of the Allied forces that helped produce the massive battlefield superiority enjoyed on the Western Front from summer 1918.