Elected to Parliament in 1784, Windham was attached to the remnants of the Rockinghamite faction of Whigs, whose members included his friends Charles James Fox and Edmund Burke.

6 Golden Square, Soho, London,[2] the son and heir of William Windham, Sr. of Felbrigg Hall, whose ancestors had long been seated in Norfolk, by his second wife, Sarah Lukin.

Windham was educated at Eton College from 1757 to 1766, where he was a contemporary of Charles James Fox and where he was noted for the ease with which he acquired knowledge, and for his success in sports.

According to Edmond Malone, Windham "was highly distinguished for his application to various studies, for his love of enterprise, for that frank and graceful address, and that honourable deportment, which gave a lustre to his character though every period of his life".

Whatever may be the diversity of opinion as to the particular nature, I believe Christ to be a person divinely commissioned, and that faith in him affords the fairest hope of propitiating the great author of the world.

[9] On 28 January Windham delivered in Norwich his first public speech, where he spoke against the war, and a few days later he wrote a remonstrance against it which was signed by 5,000 people and was presented to the House of Commons.

Upon his return, Windham sent his friend and fellow Whig MP Edmund Burke some books (recommended by a Deputy of the National Assembly) on the general state of public opinion in France in the aftermath of the beginnings of the French Revolution.

"[16] After reading Burke's Reflections on the Revolution in France in November 1790, Windham wrote in his diary: "Never was there, I suppose, a work so valuable in its kind, or that displayed powers of so extraordinary a sort.

What shall be said of the state of things when it is remembered that the writer is a man decried, persecuted, and proscribed; not being much valued, even by his own party, and by half the nation considered as little better than an ingenious madman?

"[17] Windham travelled to Paris in September 1791 and he was present at the ceremony in the National Assembly where King Louis XVI accepted the new constitution of France.

Windham wished they had been more courteous and added: "I hope that we shall be the people to keep up a little of the "vielle cour" in our manners, while we lose nothing of the solid advantages and privileges that the new system can promise".

[19] Windham supported the Royalist uprising in La Vendée and he urged the British government to aid them with the aim of restoring the House of Bourbon to the throne: "I would, from the beginning, have made this the principal object of the war".

[20] In a speech to the Commons, on 30 April 1792, he declared that he would unite with any body of men "who were determined to set their faces against every endeavour to subvert the true principles of the constitution".

[25] In the opinion of the historian Frank O'Gorman, if the Pitt government was to be persuaded to adopt the only anti-Jacobin policies that would be effective, "Windham was the only politician who might seriously undertake to accomplish these ends": He was possessed of distinguished talents and a disposition so compelling as to endear him to all.

He was daunted with the prospect of assuming responsibility for matters of state by the doubts and fears which gnawed away at the determination he could summon in his rare moments of enthusiasm and exuberance.

In a speech in the Commons that same day, Windham supported Pitt, arguing that intervention in French affairs might become a necessity if a government was formed in Paris "as we might with safety treat with".

[30] The Duke of Portland, on 3 July, urged Windham that, if he took up Pitt's offer of the Secretaryship at War, he could make it "a real efficient Cabinet employment".

[36] However, by October 1796, Windham had changed his mind, writing to Mrs Crewe: "If I could have been sure that Lord Malmesbury's despicable embassy would succeed and that peace must be the immediate consequence, I should have been out long since".

Immediately after the Peace of Amiens was signed, the Prime Minister, Henry Addington, wrote to Windham on 1 October 1801: "I think when I see you...I can satisfy you that it is not clear even upon your own Principles that we are wrong".

[47] On 5 February 1806 Windham received the seals of office to become Secretary of State for War and the Colonies in Lord Grenville's Ministry of All the Talents.

[51] Writing to Charles Grey in September 1809, Windham voiced his opposition to peace with France, even though Wellington had been driven from Spain back into Portugal.

Will it make no difference in the mass of a people, whether their amusements are all of a pacific, pleasurable, and effeminate nature, or whether they are of a sort that calls forth a continued admiration of prowess and hardihood?

But when I get on these topicks, I never know how to stop...[56]On 8 July 1809, Windham was returning to Pall Mall, London from a friend's when he saw a house on fire in Conduit Street.

As a Statesman, he laboured to exalt the courage, to improve the comforts, and ennoble the profession of a Soldier: As an individual, he exhibited a model of those qualities which denote the most accomplished and enlightened mind.

Frank, generous, unassuming, intrepid, compassionate, and pious, he was so highly respected, even by those from whom he most differed in opinion, that, tho' much of his life had passed in political contention, he was accompanied to the grave by the sincere and unqualified regret of his Sovereign and his Country.

[64] Sir James Mackintosh wrote to a friend after meeting Windham in March 1800: "His conversation is full of sense, knowledge and vivacity and his manners very gentle.

[66] Sir Nathaniel William Wraxall claimed Windham was: ...one of the most accomplished orators and individuals whom we have beheld in our day...His person was graceful, elegant, and distinguished; slender, but not meagre.

Ardent in his love of civil liberty, for the preservation of which blessing, I believe, he would as cheerfully have shed his blood as did Hampden or Sidney; it was constitutional freedom that he venerated, not a republican and impracticable emancipation from limited monarchial government...To Burke, Windham unquestionably bore some analogy; and on his shoulders may be said to have descended the mantle of Burke...Windham's talents, brilliant and various as they were, always however appeared to me more adapted to speculative, than to practical life.

[67]Henry Brougham said of Windham: ...a lively wit of the most pungent and yet abstruse description, a turn for subtle reasoning ... familiarity with men of letters and artists as well as politicians...a singularly expressive countenance—all fitted this remarkable person to shine ... [but] he was too often the dupe of his own ingenuity; which made him doubt and balance ... His nature ... was to be a follower, if not a worshipper, rather than an original thinker or actor ...

He had a scintillating personality, and political convictions so strong that they belied his otherwise scholarly and discriminating characteristics, but he lacked judgement and had a streak of melancholic instability".