Liquid fuel wasn't new (the etymology of "oil" is
olive oil, in use for literally thousands of years <
https://www.etymonline.com/word/oil>), but cheap, abundant, geologically-sourced liquid fuels were.
Whale oil may have been big business in the 18th century, but the entire history of whale-hunting produced the equivalent of a few days of present petroleum extraction in terms of fuel.
Oh, and Whale hunting did in fact continue through the 20th century, petroleum didn't save the whales, as has been discussed here: <https://edconway.substack.com/p/no-kerosene-did-not-save-the...> <https://news.ycombinator.com/item?id=43584303> (April 2025). Aristotle Onasis, whom I've already mentioned in this thread, not only owned oil tankers and supertankers, but built some of the largest whaling ships ever commissioned, specifically to hunt blue whales:
<https://www.greece.org/poseidon/work/modern-times/onassis.ht...>
<https://en.wikipedia.org/wiki/Aristotle_Onassis#Whaling>
I'm not entirely sure what Churhill knew or when, but the British Empire was already creaking (along with much of the rest of the 19th-century European political establishment) even before the onset of WWI (and was in fact a major contributing factor to that war), and was obviously weakened and foundering prior to WWII, which was the coup de grâce.