Although it is not a focus of the narrative, the fluidity of British government coalitions of the mid-19th century is striking (and key to the politics of the era, of course). Both the Whig and Conservative tendencies were coalitions more than parties, riven with factions and dissident wings. The Conservatives had Gladstone and the other Peelites who opposed protective tariffs. The Whigs had Palmerston and his like-minded band of foreign-policy adventurists.
When Russell's Whig government collapsed after a falling out with Palmerston early in 1852, the Earl of Derby formed a generally undistinguished Conservative government with tacit support of the Peelites. Disraeli became leader of the Commons as Chancellor of the Exchequer. After a summer election, Disraeli presented a budget which lifted trade barriers but tried to compensate those who would lose from it. Gladstone effectively (although perhaps a bit tendentiously) savaged it, in the process demonstrating his deep command of the budget and bringing down the Conservative government. Lord Aberdeen was called upon to form a new Whig-Peelite coalition government with Gladstone at the Exchequer.
Gladstone's triumphant budget of 1853 secured his place among the first rank of British politicians. He carried it through against considerable initial opposition within the cabinet itself, especially from the two rival aspirants to the chancellorship, Wood and Graham. His budget speech's success derived in part from his mastery of budget history, but even more from his determination to reconstruct government finance in a more rational manner. In a step devised to increase prosperity, he reduced customs duties. He made up for the lost revenue by extending income tax for seven years and also applying to somewhat lower incomes and to Ireland. Since the income tax was unpopular, and Gladstone himself was on record opposing it, the trick was to make this extension palatable. He accomplished this by extending the tax in a way as to put Britain on a path to doing away with it, by setting it at a gradually declining rate (at the end of which it would be expected that greater prosperity would bring in sufficient revenues without it, though from what sources is not clear to me, anyway).
Crimean War -- although he initial supported it, Gladstone could not sustain enthusiasm for war (which was a reversion to more typical form for him). The damage to the Aberdeen coalition was done, however, and the government did not survive the war.
Oxford reform bill -- another subject on which Gladstone changed his mind, for he had opposed the original commission of a report on reform. Gladstone was unusually willing to change his opinions, but not necessarily willing to be seen as having changed. Gladstone constructed and carried the legislation through parliament in 1864 almost unaided. Opened up Oxford to Dissenters (Gladstone himself opposed including this in the bill while supporting it in principle). Replaced government by the heads of colleges by an elected board. Permitted the opening of private halls at the university in order to provide opportunities for less wealthy students to matriculate (without transgressing the independence of the existing colleges). The bad feeling at Oxford about his role in reform ultimately led to his election defeat of 1865.
Civil service reform -- This was an issue that Gladstone (like Oxford reformer Benjamin Jowett) saw as linked to opening the university to talents. Inspired by Wood's Indian civil service reform bill, Gladstone commissioned a report from Sir Charles Trevelyan and Sir Stafford Northcote on opening the civil service to competition. He was unable to make headway on legislation, however, since he had the support of the Peelites but not most of the Whigs. Jenkins thinks that Gladstone missed an opportunity by failing to make a deal to support Russell's electoral reform bill in exchange for Russell's backing for civil service reform -- particularly since Gladstone came around to Russell's position on electoral reform before too long in any case.
The Aberdeen government was finally brought down by disagreement over how aggressively to pursue the Crimean War in January, 1855. In the vain hope of forming a renewed government under Aberdeen, Gladstone refused to accept the chancellorship under any of the possible Whig alternatives to Palmerston as prime minister. This all but handed the job to Palmerston, who Gladstone really didn't want, since it removed a principal virtue of any alternative leadership to his. Then Gladstone ended up accepting the chancellorship under Palmerston after all, only to resign it three weeks later, in conjunction with the resignation of two other Peelite ministers, because of his distaste for the direction of Palmerston's government. It took years for Gladstone's political reputation to recover from the damage done by this incident.