Final answer:
The event that caused British imports to the colonies being reduced by half was the American boycott of British goods, a response to the Stamp Act, Townshend Acts, and other imperial reforms aimed at increasing British control and revenue in the aftermath of the French and Indian War.
Step-by-step explanation:
The reduction of British imports to the colonies by half was significantly influenced by colonial resistance to British trade policies and taxation, such as the Stamp Act and the Townshend Acts. The American boycott of British goods led to a substantial decline in trade, prompting British merchants to lobby for the repeal of these oppressive measures. Parliament's attempts to raise revenue to pay off debts from the French and Indian War also led to increased taxation and restrictions on colonial industry, such as preventing the manufacturing of certain goods to avoid competition with English products, further straining the economic relationship between Great Britain and the colonies.
The involvement of interest groups and the aristocracy in British politics resulted in additional financial pressures, culminating in various imperial reforms aimed at increasing control and revenue from the American colonies. Collectively, these events and policies incited colonists to take action against what they saw as unjust economic manipulation, consequently reducing British imports as part of their protest.