Here is a CIA report on Pinyin from, I think, 1961 or so. They lay out the history of pinyin as a method of romanization (or latinization) of Chinese, and from what little I know of the topic it seems fairly accurate. What I find most interesting is the final section, which does not recommend the CIA switching to pinyin, but does suggest that
But we should at least be keeping up with the Communists in our familiarity with the Pinyin forms, and as we set up new systems we should design them with an eye to convertibility to Pinyin. Otherwise we may find ourselves stuck, in a decade or two, with passing the bulk of our material through a superfluous routine of conversions into and out of the then antiquated and artificial Wade-Giles. We have succeeded in remaining for more than eleven years the frightened ostrich with respect to a single Communist rendering, Peking, but we should not try it for a whole language.
This strikes me as a pretty bold memo. (( See, I should have worked for the CIA. I may not be James Bond, but I know a bold memo when I see one )) Adopting pinyin was seen as a pretty radical pro-Beijing step in the West for a long time. Here the CIA is suggesting that they should get ready for the change.
Google n-gram shows us that Bejing was hardly used at all in English before 1975, and only passed Peking in 1985. There are still pockets of “pinyin is Communism” around now, I expect, so it is interesting (but not all that surprising) to see the CIA bowing to the inevitable so early.