A gradualist Whig transition to liberal Constitutional Monarchy avoids the Republicanism of the American, French, Chinese Revolutions and the bloodbath of World War I. A World Order is created balancing a Concert of Europe and a global British Commonwealth.
The New England Dominion
In 1763 the Treaty of Berlin is signed restoring the Kingdom of Prussia, after its partition by France and Austria. Fearing the loss of the major continental Protestant power and the permanent upset in the Balance of Power, Pitt agrees to restore the French North American Empire in exchange for the restoration of Prussia. Frederick the Great returns to power from his exile in Holland. With the French Empire on its borders, there is less pressure from the colonies for independence in the 1760s. Nonetheless there is a growing Whig movement in America, angered at the squandering of their Quebec victories, for European power politics, as well as taxation without representation. Realizing that a stronger, centralized New England is necessary to country the French threat, the British agree to the creation of a Dominion of New England, with initially 3 seats in the British Parliament.
The Orleanist Revolution
France is less burdened by debt than in OTL, having never engaged in the 1783 war. But it still faces a debt crisis in 1788. With the crisis less severe, more moderate heads are able to prevail.
When Louis XVI refuses to acquiesce to being a constitutional king in the English style, he is overthrown and King Philippe Egalite I is installed in a Glorious Revolution mirroring that of 1688. A liberal constitution is proclaimed, a more democratic version of the existing English Parliament.
Austria is initially hostile to the dethroning of Marie Antoinette, but in 1808 the Franco-Austrian Alliance is restored with Metternich arranging the marriage of Marie Louise to the Dauphin Louis Philippe. The Orleans follow the Bourbon foreign policy of joining with the Austrians to oppose the rise of Prussia.
A Southern German customs union is organized by France and Austria, with the support of Bavaria and Württemberg to isolate Prussia.
The Orleanists support a liberal palace coup in Spain in 1808, creating a constitutional monarchy. The Spanish colonial Creoles fearing liberalization and the possible abolition of slavery, launch a brief revolt. But they create a self-fulfilling prophesy, when the liberal Madrid Monarchy proclaims the liberation of Slaves and Natives, and uses this army to put down the creole revolt. Spanish America is organized into a Federation of Panama, to consolidate trade.
In the 1811 Declaration of Parma, Britain, France, Holland and Spain announce their commitment to the principles of free trade and mutual-benefit among their colonies.
In the 1830s a corollary is added, announcing their commitment to suppress the slave trade. This begins British patrolling of the African coasts. There is a brief 1831 uprising in the Carolinas to oppose the end of slavery, but it is put down by troops from the New England Dominion.
The Qing Protectorate
In 1841, with Qing China refusing to open its ports to free trade, a British expedition marches on Peking. The occupation of the Manchu capital, leads to uprisings by the Han Chinese in the South. By the Treaty of Peking, the Qing Dynasty agrees to open all coastal ports to western trade, and to become a protectorate of the British Empire. In return the UK commits to defending the territorial integrity of all Manchu domains, including the Amur river basin border with Russia. Joint Sino-British protectorates are set up over the Kingdoms of Korea, Vietnam and Japan.
With this treaty signed, the Royal Navy agrees to ferry Qing troops to South China, to put down the Han uprising.
The Qing Dynasty enters a period of semi-colonial semi-feudal relations. The entire coast of China, is open up to free trade and Western development. The Qing court is unable to oppose the building of railroads crisscrossing its vast empire.
The Chinese National Congress is founded in 1864 to call for a Constitutional Monarchy and a Parliament to be held in Peking. In 1898 with the acquiescence of the British a limited National Yuan is established in Peking. With much of coastal China, now industrialized and filled with militant labor unions, concessions to liberal democracy are seen as a safety valve to prevent more radical revolution. A Chinese Social Democratic Party is established modeled on the British Fabians and German Social Democratic Party.