What if Napoleon was defeated in the Wars of the Coalition and Britain wins? What would the world look like, in the immediate aftermath, through to today? Are the British forced off India by native states and sepoys? Does Germany and Italy unify? What does the intellectual environment look like? Etc.
And for that matter, how would it happen? I'm hard pressed to see how.
I don't really know, TBH. Italy and Germany DID unify, btw, but the former only after the massacres of Genoa and Verona in 1852 and 1853 sparked a catastrophic revolution that ended in 1861, and the latter after the Congress of Vienna in 1872(only to break up after the end of WWII in 1946.).
It may be possible to either accelerate or delay both events, I think, though I lean towards the latter with Italy and slightly towards the former with Germany, due to the problems of the 1850s.
As for Britain? I recall that Robert Sobel wrote a story back in the 1970s in which India remains British all the way up until 1947 or so. IOTL, India became largely self-governing in 1905, though it does remain an integral part of the Commonwealth today(South Africa was kicked out in 1946 and Canada never joined. Only Australia, Tasmania, Jamaica, and New Guinea are still in today, along with India).
Speaking of Napoleonic government, there was a guy in Borealia who tried to instigate a Napoleonic-style revolt in 1845 or so. He failed, but the British reaction to this was so screwy that civil war broke out just a half decade later and in 1862, the remnants were dismantled and the Confederation of Canada was born. The rest, they say, is history.....(though there was a Territory of Borealia for a while, in what was northern Ontario, in honor of the old colony)...though I wonder what could have happened had he succeeded. Could Borealia have survived for another few decades?