No. 1 in the series "Know Your Allies" and "Know Your Enemies". The only other film produced, however, was Know Your Enemy - Japan (1945).
Three minutes in, when the narrator explains how densely populated Britain is, he says that a Briton has to get on with their neighbor as "he's too damn close". "Damn" was considered a serious expletive in 1944, hence the censorship issues around its use in Gone with the Wind (1939) only a few years before. Possibly this reflects the fact that "Know Your Ally: Britain" was made not for general release but an audience of enlisted men.
Winston Churchill did not record his famous "We shall fight on the beaches" speech until 1949 (it was delivered inside Parliament and not as a broadcast): the recording of this 9 minutes into the film is the work of an impersonator.