I don't understand Dicey's byzantine out-of-style English syntax. Please keep your answer VERY simple, as I'm not a professional historian or political theorist.
What "events of 1784" was Dicey referring to? What did Pitt do in 1784?
How did Pitt's overriding of customs "establish" that Parliament's legal sovereignty is subordinate to the electorate's political sovereignty?
The true answer to the objection thus raised appears to be that the observance of the main and the most essential of all constitutional rules, the rule, that is to say, requiring the annual meeting of Parliament, is ensured, without any necessity for Parliamentary action, by the temporary character of the Mutiny Act, and that the power of Parliament to compel obedience to its wishes by refusing to pass the Act is so complete that the mere existence of the power has made its use unnecessary. In matter of fact, no Ministry has since the Revolution of 1689 ever defied the House of Commons, unless the Cabinet could confide in the support of the country, or, in other words, could count on the election of a House which would support the policy of the government. To this we must add, that in the rare instances in which a Minister has defied the House, the refusal to pass the Mutiny Act has been threatened or contemplated. Pitt's victory over the Coalition is constantly cited as a proof that Parliament cannot refuse to grant supplies or to pass an Act necessary for the discipline of the army. Yet any one who studies with care the great “Case of the Coalition” will see that it does not support the dogma for which it is quoted. Fox and his friends did threaten and did intend to press to the very utmost all the legal powers of the House of Commons. They failed to carry out their intention solely because they at last perceived that the majority of the House did not represent the will of the country. What the “leading case” shows is, that the Cabinet, when supported by the Crown, and therefore possessing the power of dissolution, can defy the will of a House of Commons if the House is not supported by the electors. Here we come round to the fundamental dogma of modem constitutionalism; the legal sovereignty of Parliament is subordinate to the political sovereignty of the nation. This the conclusion in reality established by the events of 1784. Pitt overrode the customs, because he adhered to the principles, of the constitution. He broke through the received constitutional understandings without damage to his power or reputation; he might in all probability have in case of necessity broken the law itself with impunity. For had the Coalition pressed their legal rights to an extreme length, the new Parliament of 1784 would in all likelihood have passed an Act of Indemnity for
illegalities necessitated, or excused, by the attempt of an unpopular faction to drive from power a Minister supported by the Crown, by the Peers, and by the nation. However this may be, the celebrated conflict between Pitt and Fox lends no countenance to the idea that a House of Commons supported by the country would not enforce the morality of the constitution by placing before any Minister who defied its precepts the alternative of resignation or revolution.