Let's think about some specific PODs.
For a pre-1870 POD, I would prefer giving Lord Russell more chances. Although Ireland was his massive failure, but he did very well in Britain, passing lots of social reforms, even more than both Disraeli (who basically had zero interest in public education) and Gladstone, despite not having parliamentary majority. It was him who fought for the Great Reform Act in 1832. He was also an early and persistant advocate of a national education system (which Gladstone opposed until 1870), public health and town improvements. He was the most reform-minded non-Radical in British Parliament. Finally, he was not a heavy-handed commander like Gladstone, thus the Radicals would be able to exert greater influence after 1867 than IOTL. Here, my ultimate motive is to have Chamberlain gaining more influence during the last Russell ministry 1871-1878 ITTL, and by 1880 becoming powerful enough to discourage Gladstone from introducing Home Rule. I mean, you can't find anyone better than Russell among the Parliament Establishment with a pre-1870 POD (a Radical government can only become possible with a successful Revolution). Both Gladstone before 1865 and Palmerston were Torylite in domestic sphere.
Post 1870: another version of Irish Home Rule, or no Charles Dilkes scandal, means that Chamberlain never defect. He would eventually become PM. Chamberlain would be likely to create a party of producers' alliance against what they call "rent-seeking" interests like landlords or City, with a both labour-friendly and industry-friendly platform.
I have little hope for the Tories since the landowners and City's interests in the Tories were too big.
A small change in 1905: have Charles Mertz successful in persuading the Parliament to unify electrical standards.