> "The US in the 19th century, and the UK in the 18th-19th were highly protectionist"
This is not really true in the UK case. While protectionist policies certainly did exist on agricultural goods in the 18th century, the UK moved gradually towards free trade throughout most of the early 19th century - and then embraced it completely with the repeal of the corn laws in 1846.
In fact, the UK at that time had a policy of unilateral free trade - not imposing tariffs on imported goods even when they came from countries who imposed tariffs on British goods.
This did become a problem during wartime. By 1914, the UK was heavily dependent on imported food and a large part of the German strategy was to try to sink ships bringing food to Britain.
The one area where tariffs were still applied was on luxury goods, which were seen to have low price elasticity. (Compare to modern China, which also seeks tariff-free trade on commodities, resources, agricultural products, etc - but heavily taxes luxuries)
It wasn't until the 1930s that there was a serious swing back towards protectionism in the UK.
Indeed they moved towards a free market principle, after they became the world’s most important military power and trading empire. So then it suited them for countries to open up their markets to them.
The UK also, as you mentioned prevented their colonies and countries in their sphere of influence from instituting similar protectionist laws to develop their own industry. Instead there was a role designed for them, namely to provide cheap raw materials.
The US did the same after attaining a similar position as the world superpower later.
This is not really true in the UK case. While protectionist policies certainly did exist on agricultural goods in the 18th century, the UK moved gradually towards free trade throughout most of the early 19th century - and then embraced it completely with the repeal of the corn laws in 1846.
In fact, the UK at that time had a policy of unilateral free trade - not imposing tariffs on imported goods even when they came from countries who imposed tariffs on British goods.
This did become a problem during wartime. By 1914, the UK was heavily dependent on imported food and a large part of the German strategy was to try to sink ships bringing food to Britain.
The one area where tariffs were still applied was on luxury goods, which were seen to have low price elasticity. (Compare to modern China, which also seeks tariff-free trade on commodities, resources, agricultural products, etc - but heavily taxes luxuries)
It wasn't until the 1930s that there was a serious swing back towards protectionism in the UK.