I agree,You have a 1800's POD in the After 1900 Forum.
The better way for a superstrong Great Britain today, is a Federation (USA style) of UK,Canada,Australia,New Zealand from 1860s.
Better if American revolution had never happened and The Commonwealth of North America is in the British Federation.
If we are limited to XX century,the better way for a strong Britain is avoid WW-I,Russian Revolution,Nazism and Fascism,WW-II and Cold War.
Without all this (and remember the start is WW-I,so maybe if we avoid the Great war avoid the rest)
British Empire remains intact ,for sure, in 2010.
On the other hand in this timeline the world is less democratic and the tecnological level a bit more back...
But we can not have all.
Another cup of tea old bean?