In the thread-head article, points made by McKinley generally comport with the Republican Party platform of 1900; thus, I think that the quotes from McK are likely accurate.
I don't know about the situation in England, but there's no question that they did lose 'the Empire on which the sun never sets' for SOME reason, and the article is persuasive, if not convincing. Losing an entire Empire takes more than just economic incompetence...
So far as I am concerned, the McK quotes will stand unless you or M1968 (whoever) demonstrates that they are false or cut/paste doctored.
Try fighting two treasury-draining wars in 31 years.
The cost of maintaining an empire that covered, at its height, 25% of the Earth's surface, is staggeringly high. Witness the problems of the United States right now, and it essentially only has two colonies to support--Iraq and (arguably) Afghanistan.
What is actually remarkable, frankly, was that the British economic twin-pillars of free banking and free markets were able to sustain such an enormous Empire as long as it did.
The English lost their Empire for a variety of reasons -- two little incidents (The Great War and WWII) do come to mind. Also, extremely aggressive new powers -- Germany, Japan and yes, the US (economically aggressive). Furthermore, while many (cinlcuding me) deride the BRits for their failings, you can't help but admit that they never really made their colonials hate them like the Algerians or Veitnamese hate the French and they were also too nice to be the 'trampling on natives rights' kind of imperials -- a lot more subtle they were