After Britain established its position as a "factory of the world" through the industrial revolution, it abolished the "corn laws" in 1846, and changed from the original protective tariff to the foreign policy adopted by free trade. See corn laws and Britain become the factories of the world. With the rapid development of the industrial revolution, in the forties and fifties of 19, the British industrial bourgeoisie demanded the abolition of the protective tariff policy representing the interests of the land aristocracy and the implementation of the free trade policy representing the interests of its own class, and got what it wanted. The implementation of the free trade policy promoted the development and prosperity of British capitalism and made the industrial bourgeoisie gain exclusive political dominance. However, for colonial and semi-colonial countries, the free trade policy is an economic aggression policy.

In short, you can answer1mid-9th century.

Thank you, hope to adopt!