Roy Jenkins, Gladstone: Chapters 17 and 18, "'My Mission Is to Pacify Ireland'" and "A Commanding Prime Minister"

Gladstone recovered his balance in the opposition against Disraeli's minority Conservative government by late 1867 .  His foothold was Ireland.  Although he had never visited Ireland (and was not unusual in that respect among British politicians), its predicament had vexed him for many years.  This vexation issued primarily from his concern that the Irish situation damaged Britain's reputation abroad.  Gladstone considered himself very much a man of Europe, and it pained him when foreign leaders pointed out this illiberality in British policy (especially when he was calling them out for some transgression).  At the same time Gladstone was suspicious of Ireland as a potential drain on the Treasury.  So he was in need of a means of addressing the injustices of British rule in Ireland which didn't require spending money.  The disestablishment of the Anglican Church in Ireland fit his need.

In December, 1867, he delivered a speech at Southport declaring the urgency of addressing Irish church and land reform. Although its endorsement of disestablishing the Anglican Church in Ireland completely reversed Glasdstone's views on church and state from early in his parliamentary career, this was not, Jenkins argues, a sudden change.  Over the succeeding three decades, he had grown wary of the corrupting effects of political interference in church affairs.  He had needed to be circumspect in his public opinions, however, as a representative of the parson-heavy electorate of Oxford University.  Once he had changed to his Lancashire constituency in 1865, he was freed from this constraint.

Shortly after the Stockport speech, Lord Russell retired, thus elevating Gladstone to leader of the opposition.

In the Spring of 1868, Gladstone introduced three resolutions on Irish reform.  They carried either by handsome majorities or unopposed; Ireland was an issue which united rather than split (like electoral reform) the Liberal majority.  He followed this up with a bill to end new appointments to Irish benefices, which carried easily in the Commons though it was later rejected by the Lords.  Disraeli was forced to face the reality that his party was unable to govern. Being in no hurry to dissolve parliament just two months into his premiership, however, he announced the dissolution but delayed it for half a year on the basis that a new election should only be contested after the previous year's Reform Act had been implemented.

Gladstone conducted a vigorous campaign for his Lancashire seat, marked by some of his most noted campaign oratory.  Jenkins reprises, with humor, one of his effective riffs:

[H]e responded to the accusation that his Irish proposals would destroy the constitution by mockingly recalling that he had already known it wholly ruined  and destroyed seven times, starting in 1828 with the repeal of the Corporation and Test Acts and ending (for the moment) with the Russell government's attempt at suffrage reform.  Understandably in the circumstances, he omitted to mention that he had himself been violently opposed to the first three of the seven measures. (287)

In the event, Gladstone led the Liberals to a smashing 112 seat majority while embarrassingly coming up short in his own constituency, which turned out to be singularly resistant to the merits of Irish reform.  This was not too inconvenient for Gladstone, who had already won election from the London seat of Greenwich a week earlier.

Gladstone spent the winter recess putting together his cabinet and preparing the Irish reform legislation.  He also propitiated the queen, who had objections on matters of personnel (she didn't want Clarendon as foreign minister) and policy (Ireland) -- successfully on the former, but, characteristically, less fully than he thought on the latter.

Gladstone's Irish reform bill passed by crushing majorities of over a hundred on each of its readings in the Commons, and even passed the Lords comfortably on second reading.  The decisiveness of the votes reflected in part the increasing clarity of the division in British politics after the muddled and fluid mid-century period. But it was also a testament to Gladstone.  Throughout, Gladstone's powerful oratory, mastery of detail, skillful management of debate, and not least his attentive wooing of allies (starting with his full and careful consultation with his cabinet) and opponents (including the bishops), steered the bill to success.  The bill was threatened when the Lords backtracked on disendowment (though not disestablishment).  In the end, however, the Lords and the church hierarchy were cognizant (or made so) of the dangers entailed by standing athwart a bill so overwhelmingly supported by the Commons, and in the end Gladstone only had to accept some small concessions to win approval.

In the rest of the chapter, Jenkins surveys Gladstone's passion for rearranging his books, his delight in dispensing patronage (especially church appointments, but also grants of nobility), and his infatuation with Laura Thistlethwayte.