Plumbing the origins of 'po'

Ben Yagoda, close observer of the British-American vocabulary trade, thinks po-faced is finally making its move on American English. He could be right, though my fumbling attempts at Google Ngramming suggest there's a surgelet in usage on both sides of the Atlantic, not just ours.

I'll be gobsmacked if we manage to domesticate it, though. When I wrote about po-faced in 2004, I concluded that it was so slippery and opaque that you might have to be British to use it. As Yagoda observes, "If you don’t know what po-faced means (as I did not the first couple of times I came across it), the examples won’t be very helpful in instructing you."

My first encounter with the word came in Paul Scott's "Day of the Scorpion" (the second novel in his "Raj Quartet"*): A character describes a British child's life in colonial India as "growing up with all the other po-faced kids in a sort of ghastly non-stop performance of Where the Rainbow Ends."** The context offered no clue to its meaning, nor did the word itself: What the heck is po?

Though Yagoda is skeptical of the leading etymology, it looked pretty plausible when I was searching. Po is a well-attested English abbreviation, in use since the 1880s, of the French pot de chambre, or chamber pot. As I wrote then,

plumbing-pampered Americans should note that the po is hardly ancient history: The writer Katherine Powers remembers learning po-faced in Ireland in the '60s, when there was a po in every bedside cabinet. The relationship between the porcelain object and the adjective seemed obvious, she e-mails: "A po-faced person sports the look of absurd dignity and humorlessness that is perfectly ridiculed by calling it po-faced."

Like Yagoda, I'm dubious about a possible connection with poker-faced: Poker is an American game, and if it were the source of po-faced we should have learned that term long ago. But he's more sympathetic than I to the possibilities of the po'/poor connection. This theory was addressed back in 1999 by Michael Quinion:

Chambers Dictionary argues that it comes from poor-faced, but this is a much less likely origin, especially when you consider other British terms like potty for a child’s chamber pot, and pooh or poo for its contents, even though these are recorded much later than po-faced.

As Yagoda says, "further research is called for." And if po-faced is indeed coming to America, we can expect another round or two (or ten) of etymological debate. Consider yourself alerted.

*Thanks to former colleague Charles Matthews for turning me on to these great books even before the (also great) Granada TV series was broadcast. 
**According to Wikipedia, this is "a children's play, originally written for Christmas 1911 by Clifford Mills and John Ramsey," that is a fantasy with "themes of British imperialism."