Yup. Your challenge, should you choose to accept it, will be to have a nuclear Cold War between the British Empire and Russia (Russia's form of governement shall be left up to you)
Should you be able to kep South Africa, Canada, Ireland and Australia in the Empire, along with assorted island colonies, the Empire will probably have the necessary population base for this. India isn't a requirement, although the extra population would help the Brits immeasurably.
Central Powers victory in the Great War, with one of the elements of this or a side-effect being the success of the Hindu-German conspiracy in inciting nationalist riots and mutiny in the Indian army, from Punjab to Bengal, resulting in at least part of India forming Azad Hind/Free Hindustan. An important figure in the Provisional Government of India, "the Aryan Peshwa" Mahendra Pratap eventually becomes leader of Free Hindustan; something that will bite the Germans in the ass, as he is a radical, a socialist, and supposedly in real history got along decently with Lenin.
German-sphere India (Hindustan) becoming Soviet-sphere India could leave the British Empire, with either the Raj still in effect in parts of India or a pro-British state or states (Balochistan, Rajaputana, Burma, and so on) could make Britain the natural antagonist for the Soviet Union in the future after the Central Powers eventually become less central to the world through decline or Great War II.
The Germans gaining their African colonies back after the war, as well as perhaps additional land from the weaker Allies such as Portugal, could make Britain more involved in her African possessions. Maybe they assume control of Portuguese Africa as well, while the Germans gorge on the Belgian Congo? A firm British hand in South Africa could lead to it contributing more to the Empire by not being turned into a disastrous apartheid state by the Boer nationalists. Plus, the need for Australia and New Zealand to remain strongly integrated in the Empire wouldn't seem so ridiculous with major Soviet naval bases in the Indian Ocean.
One could also assume a weakened France after losing Great War I could fall into the British sphere, along with the rest of Allied Europe (France, Spain, Portugal, Benelux countries).
Or hell, just keeping the British Empire in Africa, avoiding decolonialism's impact on British possessions until the end of this accelerated Cold War, could give Britain the umph it needs.