Final answer:
The end of Salutary Neglect and tighter control over American colonies by the British were primarily prompted by the need to pay off debts from the French and Indian War. This shift involved new taxes and regulations that aggravated colonial discontent and set the stage for the American independence movement.
Step-by-step explanation:
British Policy Shift After French and Indian War
The change in the British policy of Salutary Neglect after 1763 was most directly the result of the need to pay debts acquired during the French and Indian War. This policy had allowed American colonies to operate with considerable autonomy, but post-war expenses led the British Parliament to pass a series of acts designed to extract revenues from the colonies to offset war costs and defend the colonies. Rejecting the previous era of lenient oversight, these acts imposed stricter trade regulations and new taxes, which ultimately fomented colonial dissent and contributed to the eventual drive for American independence.
Salutary Neglect was an unofficial British policy initiated under Prime Minister Robert Walpole that allowed the colonies to thrive economically by minimally enforcing trade regulations. However, with the conclusion of the French and Indian War, and the Peace of Paris, Britain faced an enormous debt and increased costs in administering the expanding empire. Thus, Parliament abolished the policy and enacted revenue-raising measures, such as the Stamp Act and the Townshend Acts, that were met with strong colonial opposition.
The British government hoped to have the colonies contribute to the war debt and the cost of their own defense and governance. This abrupt policy reversal from Salutary Neglect to more directly managed colonial affairs exacerbated tensions, ultimately leading to a colonial push towards self-governance and the questioning of British authority.