What is the origin of the lake tank image that has become a meme? (2021)

Since Know Your Meme doesn't give the reference for why it's a lake, maybe not everybody is familiar with british lore:

The mythical Lady of the Lake:

Probably best known via Monthy Python:

Strange women lying in ponds distributing swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony.

In short: She teaches Lancelot arts and writing, infusing him with wisdom and courage, and overseeing his training to become an unsurpassed warrior.

https://en.wikipedia.org/wiki/Lady_of_the_Lake

https://tvtropes.org/pmwiki/pmwiki.php/Main/EnigmaticEmpower...

This reminds me that Monty Python and the Holy Grail contributed actual historical knowledge about Arthurian legends to my knowledge base while growing up. Other examples of Python unintentional education include knowing the names of a myriad of obscure cheeses (the cheese shop skit), a shocking number of anachronistic synonyms for death (the parrot skit) and notable contributions of the Roman Empire (Life of Brian 'What have the Romans ever done for us?' skit).

While it didn't contribute to my GPA at the time, I'm sure I could name more notable philosophers than any other 8th grader in my school (philosopher's song skit). However, in high school it did spark the interest to look up and read about each of the philosophers in the song.

The problem is that comedy is frequently not factually accurate.

Roman Imperial contributions? Was Roman wine better than pre-Roman wine in that region? Did they improve sanitation, irrigation, medicine etc.? Rome was an oppressive slavery based society.

Then what about the Spanish Inquisition sketch? It keeps repeating "fanatically devoted to the Pope"" The Spanish inquisition was an arm of the Spanish monarchy, at least two Popes tried to shut it down, and some historians have suggested one of its aims was to reduce the power of the Papacy.

I do like the Philosopher's Song, the Dead Parrot and Cheese Shop.

Other comedies are no better. Black Adder has a witchfinder (an early modorn innovation) in a Medieval setting.

Pop culture is not historically accurate!

The "what have the Romans done for us" sketch is partly about Rome, but largely a disguised defense of the British Empire.