.....with the USA isn't something that was borne out of mutual fondness and friendship. Quite the opposite. The "Special Relationship" began when the USA declared war on Japan. Japan had an allied agreement with Germany, so Germany then declared war on the USA. The USA didn't come riding over over the hill, like cavalry to the rescue for the UK. As a consequence, military co-operation was a necessity and so was intelligence. Churchill was reluctant to reveal Operation Ultra to the USA but when he did, that was the start of the ridiculously so-called "Special Relationship" In 1934 the USA developed a plan called War Plan Red. This involved the possibilty of the USA declaring war on Britain and the British Empire. The initial stages of the "war" would involve invading Canada and British held Carribean territory. The "Special Realtionship" was war time thing folks. Nowt else.
https://www.bbc.co.uk/news/av/57438410