Whistling Jack Smith 'I was Kaiser Bill's Batman'

A hit from 1967 - info here - a lot of the easy listening hits of the 60s confused me as a child when I heard them on the radio - I used to take them quite literally - 'Windmills of your mind' what was that all about? (According to the wiki on it 'The song illustrates a person's mental state after a romantic break-up, relating the way emotionally charged thoughts and memories can run in tortured circles'. Oh. Nothing about windmills like 'A mouse that lived in a windmill in old Amsterdam' then')?Similarly this hit - who was Kaiser Bill and why did he need someone to dress up as Batman for him?