"Empire Trade", a 1934 British propaganda film, provides some historical context (you can view it at the excellent Colonial Film website; I got to it through a University of Exeter online course on the British Empire). Here low tariffs within the British Empire are touted in terms of the jobs brought to the home country by exports to the colonies and dominions, and the the raw materials from around the empire that feed British industry.
Visually, prosperity at home is represented by belching smokestacks, white-hot furnaces, and smoking locomotives.
|Rubber plantation in Malaya. "The amount of rubber produced here alone |
is nearly twice as much as the rest of the world's output, and so
forms a tremendously important addition to our Empire resources."
|Coconut plantation in Malaya. "This chap doesn't have to wait for the fair |
and the coconut shies to come to town; he can have 'em for breakfast every morning."
|Floating logs in Canada. "The watermen, who see to it that these logs float downstream without |
jamming, have an exciting time." A few frames later, some of them fall in the water.
|South Africa. "Her most important industries are diamond and gold mining, |
both developed by British engineers, equipped with British machinery."