This is my first comment on this subreddit (hopefully I am following the rules correctly). Smith’s Wealth of Nations did have an impact on British policy after its publication. The Wealth of Nations was first published in 1776, during the Scottish Enlightenment, and sales were good enough that it sold out within six months (according to John Rae). John Rae wrote a biography of Adam Smith and within it, he details certain British policies that were influenced by Smith. He spends a bit of a paragraph detailing policies made by British PM Frederick North (Lord North). Lord North in 1777 imposed taxes with one being the tax on man-servants (Smith calls them slaves). The idea is found in Book V Chapter 2 Part 2 Article 2 (section titled Taxes upon the Profit of particular Employments). 1778, one of the duties imposed was on uninhabited houses which can be found in Book V Chapter 2 Part 2 Article 1 (section titled Taxes upon the Rent of Houses). In 1779 Smith was consulted by statesmen Henry Dundas and Frederick Howard the Earl of Carlisle on the subject of free trade for Ireland. While Rae is a good biographer, there is actual proof of these interactions. There is a letter from Smith to Howard, and proof of Dundas by an application made by the Board of Trade. Smith does recommend free trade in these letters even saying that he would not mind if Ireland were able to export to British colonies even though Ireland had no part in setting them up. A later British PM, William Pitt the Younger, also quotes Smith as an influence. Pitt goes so far as to name Smith during a 1792 speech on the prosperity of the nation. Pitt says that he believes Smith will “furnish the best solution to every question connected with the history of commerce or with the system of political economy.” The Eden Agreement definitely contains Smith’s ideas on duties (he was against them).
Smith was writing during a time when mercantilism was very popular. Mercantilism is protectionist and looks to maximize exports while minimizing imports. It looks to increase the monetary reserves within country by forcing this positive balance of trade. Usually the mercantilists accomplished this through government channels. Smith writes an entire book in Wealth of Nations on mercantilism (Book IV Of Systems of Political Oeconomy) where he says that the mercantilist policies are useless or harmful. Any policy that came from Smith aimed at reducing the barriers to freer trade would be taking inspiration from Book IV of Wealth of Nations. Book V is all about taxes and the revenue of the sovereign which is where Lord North took inspiration from. For convincing arguments on freer trade, Book IV includes Smith’s opinion on how negative mercantilist policies are and how thinking of wealth in this way (monetary reserves) actually keeps Britain worse economically. It was convincing to the new wave of thinking as the Industrial Revolution was taking place. For convincing arguments on taxes, Smith made quite a few. Smith was not against taxes or publicly provided goods. Book V is on the different ways Smith thinks those taxes can be raised. Smith believed that taxes should be fair (in agreement with the condition and ability of tax payers), efficient (collecting taxes shouldn’t cost more than taxes raised and taxes should not have a negative impact on the economy), certain (taxpayers know the ins and outs of the taxes), and convenient (taxes should be easy for the taxpayer).
The rest of the Wealth of Nations is filled with discussions on how trade works, how markets work, some conjectural history on mankind’s stages, inflation caused by silver from the New World, etc.
Sources:
John Rae Life of Adam Smith 1895
William Pitt The War Speeches of William Pitt, the Younger 1940
Adam Smith An Inquiry into the Nature and Causes of the Wealth of Nations 1776