I think some alternate realignments could have moved the Liberal Party away from free trade and towards pro-tariff position (of course in any cases they would support tariffs on manufactures only, as I expect them to still use the same old "Free Food" slogan to retain working class support).
IMO a potential POD is between 1880-1885. At that time, around two-third of the party membership were bourgeouis a.k.a industrialists, merchants, bankers and intellectuals, and the Liberal Party was decisively Britain's party of business and commerce. The rest were either labour radicals, Gladstonian ideologues or Whig/Peelite aristocrats.
My POD is to have Gladstone dying either before or after 1885 general election and remove Irish Home Rule, then Chamberlain managing to grasp party leadership from the Whig Lords like Harthington. Then, sometime later, most of the Whig aristocrats defecting to the Tories, causing the Liberal Party to be dominated by the bourgeouis, including those who became Liberal Unionists IOTL (labour radicals were just a small fringe at that time). Now, global economic trends would come to play: the Long Depression and the rise of protectionism in Continental Europe. These trends, together with the rise of American and German industries, would increasingly threaten many British industrialists, most of whom would support the Liberals ITTL without Irish Home Rule, and, including Joe Chamberlain himself (whose cutlery manufacturing business was under threat of German competition IOTL and also ITTL). Industrial bosses, possessing much greater influence over the Liberal Party ITTL, would attempt to push for certain forms of tariffs on manufactured goods that face stiff competition abroad, for example, electrical goods, chemicals or cutlery and tools. Joe Chamberlain himself might also incline to introduce those tariffs to gain extra support for social reforms. However, they would be unified in not imposing food tariffs to keep workers' food bills and hence wages down.
IMO, the Liberals ITTL would develop in a similar way to the Republican Party in the US, or the National Liberals in Germany. I mean, they would become the party of robber barons, but still more open to social reforms than the GOP.
The Tories ITTL could become a rural fringe party. Or, they could become a centrist Tory Democratic/One Nation Party that draws support from farmers, aristocrats, landlords and a large part of the working class. In either case they would dominate the House of Lords and rely on it. In the latter case, they would be destroyed once the Labour Party emerges and steals all of their working class support.
How would policy-making differ from OTL? Well, I believe that some forms of industrial policy, for example, "internal improvements", or state subsidies of research and development (I mean, similar to the way the German state subsidized the application of Haber-Bosch process in large-scame production IOTL), would emerge well before WW1.