Possible pod: Have the British be a bit harsher on the negotiations with the French and the Spanish in 1762-1763 and news of the British capture of the Philippines reach Britain faster than otl. This would allow Britain to have its otl colonial empire as of 1764, but with the addition of the Philippines, a British Dunkirk and/ or Calais instead of cancellation of French usage rights at Dunkirk, Cuba instead of East Florida, Senegal including Goree, Guadeloupe (leaving France with Minorca instead), Martinique (with France having Canada instead) and St. Lucia (with France having Tobago instead). The Falklands Crisis of 1770 would proceed as in otl, but with Britain successfully gaining the Falklands under threat of war with Spain. The American Revolutionary War, with a French Canada, would be replaced with a French war to retake Nova Scotia and capture the United States, only for France to lose the United States and Canada. The additional colonial losses of France in the Seven Years War would weaken the French Navy, leaving it unable to send ships to besiege Gibraltar (Minorca being ceded by France to Spain) and causing Spain to fail to recapture Gibraltar (except with a bit more Spanish mainland territory lost to Gibraltar), the Bahamas, Jamaica, West Florida and Cuba after being combined with the losses of Spanish revenue from Cuba and the Philippines. Following the British victory in French Canada, the British would recapture and successfully defend Calais and Dunkirk. France would regain Calais and Dunkirk only by exchanging Tobago (held by France in the 1770s instead of St. Lucia) and St. Lucia (captured in 1781 by France instead of Tobago) and by not getting Senegal back, leaving the French Canadian War a defeat for France except for Calais and Dunkirk and the latter gains not helping France's financial situation until the French Revolution began.
During the French Revolutionary Wars, the French would lose French India (without returning to France at the end of the Napoleonic Wars, the French got St. Barthelemy and Saint Martin back in exchange for losing French India) and Malta to Britain, while the British conquest of Puerto Rico, the Virgin Islands and Trinidad in those wars would succeed. The Spanish would lose Louisiana and East Florida to the still British Thirteen Colonies and West Florida respectively, lose the Spanish East Indies to a British invasion in 1797 and would not get Minorca and the remaining Balearic Islands back in 1802. In the Napoleonic Wars, the French would lose Saint Martin and the Dutch would lose their Caribbean islands and the Guyanas to Britain without returning to France and the Netherlands and with Britain having Saint Lucia, Tobago, Guadeloupe and Martinique. French Guyana, St. Bartholomew, Mauritius, Reunion and the Seychelles would join the permanent losses of France to Britain over 1809-1810 and the Ionian Islands would become British in 1814. The rest of the French Revolutionary and Napoleonic Wars would proceed as in otl. Following the Napoleonic Wars and the Congress of Vienna, the opportunity would be taken by Britain to retake Calais and Dunkirk, enforce British control of Heligoland since 1807 and capture Corsica in the congress while enforcing British control of Argentina and Uruguay since 1806, British control of Indonesia and Ceuta since 1810 and British control of Malaysia since 1786. Singapore would become British in 1819 as in otl. The Dutch colonies in South Africa and Ceylon would become British as in otl and the Dutch would lose the Belgian Revolt to Belgians.
In the 1820s, the British would annex Pantallearia as a part of Malta and the Greek War of Independence would see the formation of Greece, Romania enlarged with Bulgaria and Serbia as independent nations due to greater Russian success. The British would oppose France's invasion of Algeria and would invade Algeria, Tunisia and Morocco in the 1830s-1880s to replace France. The Opium Wars would soon cost China Hong Kong and concessions in Shanghai, Tianjin and Hankow to Britain and the British would conquer Afghanistan and British India (including Pakistan and Bangladesh) around the same time. The Crimean War or its equivalent would result in territorial status quo in exchange for Russia's demolishing of its Black Sea Fleet.
The Austrians would crush unification attempts in Germany and Italy, leaving Italy divided and non-existent as a unified nation, while Germany would be Austrian-controlled instead of Prussian-controlled. The enlarged Austria with non-Prussia Germany and Italy excluding the Papal States would cause Britain to receive Sicily, Sardinia and Calabria to prevent the Austrians from becoming too powerful in Italy and the Mediterranean and encourage Britain to align with France to prevent Austria from becoming too powerful in Germany and further westwards in Europe, while leaving a still British controlled and personally unified Hanover British annexed and controlled.
In the late 1870s, the Bulgarians would gain independence from Romania in 1876, and get Macedonia in the 1877-1878 Russo-Turkish War plus its otl 1911 borders in the same war while the Serbs would have their otl 1911 borders, Montenegro, Kosovo, northern Albania and Bosnia, the Greeks would have their 1911 borders with regard to the Ottoman Empire and southern Albania and the rest of Albania would gain independence in 1885. The British, alarmed by such gains, tried to make sure that the Greeks didn't gain too much Aegean coastline and the Bulgarians only gained non-coastal Macedonia and Eastern Rumelia. The Serbs were allowed to keep their gains because of Austria-Hungary's extra power with the latter's incorporation of northern mainland Italy and non-Prussian Germany. The British decided to take the opportunity to annex Cyprus, the Dodecanese, Tenedos, Limnos, Gallipoli, Egypt, Libya, Tunisia and the non-Turkey Levantine nations with a Mediterranean coast, leading to an Anglo-Ottoman War over 1880-1885 with the British accomplishing such objectives and the suppression of the Urabi Revolt around the same time. The 1870s (1874) also had the British expand their colonization of Malaya (Penang and Melaka under the Straits Settlements, the other Strait Settlement of Singapore being counted separately from Malaya) to include the Federated Malay States of Negeri Sembilan, Selangor, Perak and Pahang.
The British obsession with the Ottomans and the non-Ottoman Balkans would delay the British involvement in the Scramble of Africa into the 1890s, but that decade would see the British kicking off colonization in Gambia, Sierra Leone, Ghana, Nigeria, Cameroon, South Africa, Zimbabwe, Botswana, Zambia, Kenya, Somalia (which would come with otl British Somalia and otl Italian Somalia combined due to Rome-controlled Italy being divided with the British, the Papal States and the Austrians), Eritrea and Sudan plus the British gains of Algeria, Tunisia, Libya and Egypt from the Ottomans on the African continent. A Prussian (without non-Prussia Germany) attempt to exchange Heligoland and Hanover for the Prussian African colonies in Togo, Cameroon, Namibia and Tanzania in the same decade would fail, though. British India would regain control of Afghanistan and in exchange for reparations, would gain a Russian Turkmenistan and Tajikstan. British colonization of Sabah would also begin in 1888 and in 1848 for Labuan.
The First Sino-Japanese War, the Triple Intervention, the subsequent carving up of China and the Boxer Rebellion would see China losing Tianjin and Wuhan (Hankow) concessions, Korea, Taiwan and the Pescadores to Japan in 1895-1899, Qingdao and the rest of Shandong plus a Tianjin concession to Prussia in 1897-1898, Guangzhouwan in 1898 (in addition to the French concessions in Shanghai, Wuhan and Tianjin) to France, the New Territories as reinforcement for Hong Kong and Weihaiwei to Britain in 1898 (in addition to Hong Kong and the British concessions in Shanghai, Tianjin and Hankow), Port Arthur, northeastern China and a Tianjin concession to Russia in 1898 and Tianjin concessions to Austria-Hungary-Germany, Italy under the Papal States and Belgium in 1901. In the Russo-Japanese War, the Japanese would gain as much territory as the war's otl counterpart and would cede an-ex Russian and an ex-Japanese Alaska to a still British North America comprising of Canada and the United States. The British expedition to Tibet in 1903 would succeed in annexing Tibet to British India and the British would conquer Burma and Siam in the same 1900s (the British conquest of Burma having been delayed to the 1900s due to Algeria and the rest of the Ottoman Empire being prioritised first). Also, Australia and New Zealand would stay British in sovereignty, the Mosquito Coast would stay British in sovereignty and the Unfederated Malay States of Johor, Terengganu, Kelantan, Kedah and Perlis would be added to the British empire as of 1909. The British empire would also add Brunei to the empire.
In 1911-1912, the British would annex Morocco (including Tangier) instead of France and would also annex Spanish Morocco and the Rif including the already British Ceuta and the still Spanish Melilla, Plazas de Soberianas, Canaries, Western Sahara, Sidi Ifni, Rio Ifni and Cape Juby. The timeline would butterfly the Italo-Ottoman War into a conflict with Italian Papal annexation of Turkish Anatolian coastline instead of annexing Libya and the Dodecanese. The First Balkan War would proceed as in otl, but without Serbian involvement due to Serbia being territorially satisfied with the Ottomans, without Albanian revolts and Albanian involvement with Albania being independent without having to fight the Ottoman and with the Bulgarians satisfied with Macedonia, Nis and Pirot and able to prioritise their troops and gains against the Ottomans, although the Ottomans, Bulgarians and Greeks would be able to send more troops in Thrace. The First Balkan War would end in a similar result to otl for Greece and Bulgaria, but with Bulgaria satisfied with Macedonian and Thracian gains that the Second Balkan War would be butterflied or would be aimed at attacking the Ottomans instead of Serbia with Serbia's neutral approval, Greece's neutral or aligned approval and Romania's neutral approval and Ottoman defeat in that war if that war still occurred. The British would also beat everyone else for the South Pole and Antarctica and had already ruled South Georgia, the Falklands, Ascension Island, Tristan da Cunha and Saint Helena for added measure.
With a 1762 pod as mentioned above, one would expect WW1 (especially 152 years after 1762 in 1914 as in otl) to be butterflied, especially with a still British colonized instead of an independent America, a Germany annexed into Austria-Hungary except for British Hanover and Prussia, an Italy annexed into and divided among Austria-Hungary, the Papal States and Britain and a Bosnia annexed into Serbia and butterflying Gavrilo Princip, the Black Hand and Archduke Franz Ferdinand's assassination. For the sake of discussion, let's assume a WW1 analogue in the late 1910s or the 1920s similar to otl WW1, but with Bulgaria neutralised out of the Central Powers (cancelled by Serbia not having Nish and Pirot and being forced into defeat and combat around Belgrade in WW1's first year and Serbia and Bulgaria being able to supply the Ottoman Empire with ammunition), Ethiopia joining the Central Powers instead of Bulgaria (so, Eritrea and Somalia would be defended by the British and once the German Prussians, Austro-Hungarian-Germans and the Ottomans lost, the British could recapture Eritrea, Somalia and Ethiopia and avenge WW1 losses of Eritrea and Somalia and the 1868 colonial defeat in Ethiopia), the British Empire still having its Dominions and the United States/ the Thirteen Colonies attached to it (so the British would have more troops to divert the Austro-Hungarian-German and Prussian troops no longer needed to invade Serbia and Russia from Russia to France, presumably Austrian military defeats would encourage Italian nationalist rebels and the Papal States to join WW1 similar to otl Italy in WW1, but with Calabria, Sicily and Sardinia being British controlled and providing British instead of Italian reinforcements for Italy) and having the US's worth of English speaking soldier reinforcements reinforcing Britain and France in years 1 and 2 instead of years 4 and 5 cause Austria-Hungary-Germany to retreat en masse from France and Belgium in year 3 instead of year 5 with a Prussian-led Germany, followed by a Prussian, Austro-Hungarian-German and Ottoman defeat in year 4 of WW1, an Ethiopian and Eritrean defeat in year 6 or the 2nd year of the interwar period and a Somalian defeat a year after Ethiopia and Eritrea. The Bolsheviks, if they still took power, would want and would be able to take Russian claimed objectives and prestige with the victorious Entente together. The postwar peace settlement, with a more tangible defeat and conquest of Germany's as Prussia's and Austria-Hungary's as Austria-Hungary-Germany's prewar core territory, would see Prussia and the Germany portions of Austria-Hungary-Germany lose otl WW1 territorial losses as in otl and face partition elsewhere, including the restoration of British Heligoland and Hanover. The partition of Austria-Hungary would proceed as in otl and the partition of the Ottoman Empire would see Britain taking and successfully defending European and Asian around the Dardanelles Turkey from Turkish nationalists, although the Turkish nationalists would enjoy the same success against other Entente members as otl. The stab in the back myth would be butterflied for the defeated Central Powers and Ireland would stay British forever with a failed independence war.
In the interwar/ post-WW1 period, the British would take advantage of Sykes-Picot and general European peace to seize the Arab Middle East and Iran (including the British since 1839 Aden and French Djibouti), Bhutan, Nepal, Panama for a delayed Panama Canal, Mozambique for the Cape to Cairo Railway, Rwanda, the mainland Spanish port of Cadiz and Congo for its wealth and keep Weihaiwei. A WW2 analogue in Europe would be butterflied, butterflying decolonization and still allowing Britain to annex Sarawak and Rockall despite the butterflies, but with its empire intact for the last 2 annexations. Perhaps, when the Japanese invasion of China failed without escalating into war with Britain, the Japanese ceded Taiwan and some ships to Britain in exchange for cash to pay for war losses and reparations and British intervention for China might allow Britain to annex the Japanese Home Islands including Sakhalin and the Kurils into the British Empire while China regained mainland East Asia including Mongolia, Manchuria and Korea from Japan. Britain would have the world's largest empire in the 1950s when it ruled everywhere mentioned as British controlled in this post in the 1950s.
Note: Unmentioned British colonies would be otl British (or Dominion turned into British colonies) still kept and ruled as part of the British Empire as in otl or retaken if permanently lost by Britain before the 1762 pod and kept as British as of the 1950s.