On 8 July 1776 he asked Lord Rockingham to arrange for a remonstrance to be sent to the King when war broke out in America, so the Americans would see "that there is still in the country a body of men of the first rank and importance, who would still wish to govern them according to the old policy".

On 27 December Fitzwilliam wrote to Dr Henry Zouch against parliamentary reform and that the cause of the present discontents was: ...not the corruption, not the lack of independence, not the want of patriotism in the House of Commons, but the unwise and desperate exercise of the royal prerogative to choose its own Ministers, by the dismission of those who have the confidence of the people, and the appointment of those who have it not.

...[Pitt was] a young man whose ambition is so restless, and boundless, that nothing will satisfy him but being first: while to gain the object of his passion, he cares little by what road he reaches it, and meanly submits to creep up the backstairs of secret influence.

As he wrote to Lady Fitzwilliam on 4 September: "Having experienced very closely and very attentively his Lordship's conduct of late, and consequently having formed an opinion of his present principles, I can see no reason to expect that as an honest man I shall ever be able to give support to his administration, and therefore as a fair one I must decline receiving any favour at his hands".

He criticised Lord Camden's proposal that the Regent could create new peers only if the two Houses of Parliament consented: "[This was] in the highest degree unconstitutional, and he should, in consequence, think it his indispensable duty to come forward with a declaration condemning all such doctrines as repugnant to the principles of the British constitution".

He objected on constitutional grounds giving the government discretionary power to augment the armed forces without fully laying out the circumstances, and that war with Russia would be "unjust, impolitic and in every way detrimental to the interests of this country".

[49] Upon reading Burke's An Appeal from the New to the Old Whigs, he wrote to him on 18 September: I thank you heartily for the pamphlet, and for the authorities you give me for the doctrines I have sworn by, long and long since: I know not how long, they have been my creed: I believe, before even my happiness in your acquaintance and friendship, tho' they have certainly been strengthen'd and confirm'd by your conversation and instruction—in support of these principles I trust I shall ever act, and I shall continue to attempt their general propagation;—whether by the best means, is matter of speculation: but by the best, according to my judgement—nothing can make me a disciple of Paine or Priestley, nor any thing induce me to proclaim, that I am not so, but in the mode I myself think the best to resist their mischief—private conversation and private insinuation may best suit the extent of my abilities, the turn of my temper, and the nature of my character...[50]1792 saw Jacobinism gaining support in Sheffield and in late December an anonymous correspondent informed Fitzwilliam's friend Zouch of the increasing number "of the lower classes of manufacturers" professing "to be admirers of the dangerous doctrine of Mr Payne, whose pamphlet they distribute with industry and support his dogmas with zeal".

[63] When France announced that King Louis XVI was to be put on trial, Pitt recalled Parliament by calling out the militia, an action Fitzwilliam thought unwarranted and designed to curry favour with conservative Whigs.

Fitzwilliam declined to meet Pitt with the Duke of Portland on 13 June as he was organising the Volunteers in the West Riding but his objection went deeper: "However frequently I have thought on the subject...it never occurs to me without presenting itself in some new point of view, which generally tends to render decision more difficult".

[79] On 23 June Fitzwilliam wrote to the Duke of Portland that he believed the government had moved to the Whig position and that "for my own part I am now ready, not only to adopt the opinion that a junction should take place, as your sentiment, but to advise it as the genuine offspring of my own judgement...[his only condition was that] as much weight and sway should be given to us as possible.

[82]On 18 August Fox wrote to his nephew Lord Holland: I cannot forget that ever since I was a child Fitzwilliam has been, in all situations, my warmest and most affectionate friend, and the person in the world of whom decidedly I have the best opinion, and so in most respects I have still, but as a politician I cannot reconcile his conduct with what I (who have known him for more than five-and-thirty years) have always thought to be his character.

[86] He wrote to Henry Grattan on 23 August: "The chief object of my attempts will be, to purify, as far as circumstances and prudence will permit, the principles of government, in the hopes of thereby restoring to it that tone and spirit which so happily prevailed formerly, and so much to the dignity as well as the benefit of the country".

Lord Grenville however interpreted the meeting as deciding that Fitzwilliam "should, as much as possible, endeavour to prevent the agitation of the question during the present session; and that, in all events, he should do nothing in it which might commit the king's government here or in Ireland without fresh instructions from hence".

[89] On 18 November Fitzwilliam wrote to Burke to reassure him: "the business is settled: that I go to Ireland—though not exactly upon the terms I had originally thought of, and I mean particularly in the removal of the Chancellor, who is now to remain, Grattan and the Ponsonbys desire me to accept: I left the decision to them".

On 10 January he wrote to the Duke of Portland that "not one day has passed since my arrival without intelligence being received of violences committed in Westmeath, Meath, Longford and Cavan: Defenderism is there in its greatest force...I find the texture of government very weak" and chaotic.

However he "endeavoured to keep clear of any engagement whatever" on Emancipation but that "there is nothing in my answer that they can construe into a rejection of what they are all looking forward to, the repeal of the remaining restrictive and penal laws": I shall not do my duty if I do not distinctly state it as my opinion that not to grant cheerfully on the part of government all the Catholics wish will not only be exceedingly impolitick, but perhaps dangerous.

... On most of these points I should have written to your lordship sooner but the state of public business has really not left me the time of doing so; and it is not without very deep regret that I feel myself under the necessity of interrupting your attention by considerations of this sort while there are so many others of a different nature which all our minds ought to be directed".

Two days after he sent the Cabinet's demand that they "inform you in the plainest and most direct terms that we rely upon your zeal and influence to take the most effectual means in your power to prevent any further proceeding being had on that Bill until his Majesty's pleasure shall be signified to you with regard to your future conduct respecting it".

He wrote to Fitzwilliam on 20 February that recalling him: ...was the most painful task I ever undertook; [but it was] my opinion, and I call it mine, because I chose to be the first to give it, and I was, I believe, the only member of the Cabinet who gave it decidedly, that the true interest of government...requires that you should not continue to administer that of Ireland.

The Duke of Portland wrote: If any injury has been done to you, if any blow has been aimed at your political character and reputation, it is I who have attempted it; revenge yourself on me, renounce me, but assist in saving your country—I will retire, I will make any extirpation or atonement that can satisfy you—you are younger, more active, more able than I am, you can do more good.

Pitt was determined to use the Bill as an excuse to get rid of the Whig government in Ireland, spurred on by "secret, unavowed, insidious informations" and breaking the terms of the coalition agreed with the Duke of Portland.

Are they to range at large, in every town and every house, preaching their doctrines, and perhaps even buying proselytes?—are Englishmen to be sent to Paris to be witnesses of the successful result of audacious usurpation, and of the elevation of Tom Paine, from a Staymaker to a fine Gentleman, from an Exciseman to a Sovereign, as the reward of the Rights of Man and the Age of Reason—I fear Restriction and Coercion will avail little against the influence of example—but our Ministers have made up their minds, to save Jacobinism, at its last gasp, and the experiment of shaking hands with it...[121]Fitzwilliam wrote to Adair on 12 September that he would support the government on the war and "on all occasions where they support establishment against innovation, monarchy and aristocracy against the inroads of sans-culottism; but beyond these points I profess no friendship or goodwill towards an administration from which I have received such gross ill-treatment".

In 1800 he spoke again, declaring that he would support a Union but only if it would really unite the two kingdoms together, and that the penal laws were "framed against a particular description of persons which now ceased to exist: they were directed against superstition, bigotry and disloyalty; and therefore should not affect the liberal, the well-meaning, and the loyal Catholics of the present day".

However, in February 1800 Fitzwilliam openly disagreed with Fox's desire for peace with France because the national interest called for a prosecution of the war at least until the enemy accepted the status quo ante bellum, although he criticised the government for conduct of it.

[142] On 3 November Fitzwilliam delivered his speech against the peace, describing it as "a hollow and precarious truce...for the two islands of Trinidad and Ceylon, this country had been nine years engaged in war, and had wasted some hundred millions of money, and the lives of thousands of her subjects".

New occurrences and change of circumstances will, I hope, bring us together again—but still I am anti-Gallican: I ask not, what sort of Government prevail, but under none, can I submit patiently to the strange assumption of power over independent nations, daily making by France.

He still opposed Fox on the abolition of the slave trade but did nothing to stop the government from passing it, though he did speak in the Lords on 24 June 1806 that he "felt rather alarmed at the consequences the resolutions might produce" but "he could not help feeling disposed to support them".

... Its primary interference in civil matters has been approved in that quarter [the regent] to which alone it looks for approbation, the effect of which I cannot contemplate without alarm—it is this that I am anxious to meet in the earliest stage, to prevent its assuming the dangerous form of an acknowledged precedent.

Fitzwilliam conceded that such a scheme would improve the system, as he wrote to Lord Grey on 22 March, "but ninety other plans would do as much, and with me the question is, is it for the advantage of the country, and for the good of the public to moot the subject at all—where are you to limit alterations, at what point are they to stop?

Such unblemished purity and such unobtrusive intrepidity, such generosity of feeling, firmness of purpose, and tenderness of heart, meeting in one of high station and princely fortune, commanded the affection and confidence of the public; and Lord Fitzwilliam enjoyed them, beyond even those of his own class who united much greater reach of understanding and more assiduity of business to superior personal accomplishments and advantages.