Fancy A Cup Of Tea?

[anarchist_nomad]

cheshcat and I have four cats[*]. The two girls -- Stumpy and Chirp -- live near Chicago, at the Event Horizon, with their uncle gyades. The other two -- The Boy and Giles -- live with us at Skullcrusher Mountain in Oxford. The Boy was imported from the States in 2006, whereas Giles (see icon) is a born and bred British cat.

He proved his heritage yesterday. cheshcat left a cup of tea momentarily unattended in the living room. When we turned around, Giles was helping himself -- happily lapping the tea up out of the mug. Oi!

While I am ruminating on contrasts between the two sides of the pond, can somebody please explain to me the difference between "while" and "whilst"? Stateside, I don't know anybody who uses "whilst". Here, however, I see both in fairly common usage. When is one appropriate and when is the other? One hundred points to the person who gives me the best explanation!

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[*] Not counting Nona, who lives with polymorphism in Nebraska now.