During the 19th Century, one of the greatest debates in British politics involved the extent to which government had a role to play in the promotion of trade. In the centre of this issue stood Joseph Chamberlain, the radical MP for Birmingham, who fought on the side of “tariff reform” and the establishment of Imperial Preference and British rule over Ireland. For a Liberal Party that supported free trade and promoted Irish Home Rule, this proved an anathema, resulting in Chamberlain leading his supporters into alliance with the Conservative Party. Although he served in a number of senior roles, including a brief stint as Leader of the Opposition, Chamberlain never became Prime Minister, an office many considered him destined to hold.
It could have all been very different.
In 1884, William Gladstone embarked on a speaking tour of the North of England, at one point being held up in the Yorkshire Dales in a thunderous rainstorm. Although he took ill, his recovered from the cold by the time he returned to London, spearheading the 1884 Representation of the People Act which served to greatly expand the franchise, mainly to the benefit of Liberal voters. ITTL, Gladstone forgets his coat, leading to a far more deliberating bout of flu that prevents him from spearheading the Bill through the House of Commons, thereby allowing the Conservative opposition to weaken many of the provisions. As a result, the Liberals slump to a narrow defeat at the next General Election (which in OTL they won), prompting Gladstone to resign instead of taking up the promotion of Irish Home Rule. As a result, Chamberlain never defects, although he remains irked by many factions of the party.