In a glass

George ordered the drink without schapps. But, when Toby Esterhase appeared (in the guise of Herr Jacobi), he ordered them both schnapps anyway!

Well, I don't know why Smiley would like to order a coffee in a glass, I always found that strange.
In Switerland, you usually get coffee in porcelain cup. However, coffee+schnaps is served in a glass (the same as for tea), hence the waitress' reply

I just re-watched the series after a couple of years, and one of the running themes is the discomfort George's generation has with non-English manners -- even in England -- as well as general tension among Europeans generally. I think the glass scene is meant to show George's irritation with the officiousness and coldness of the Swiss. Part of the fun of the novels is all the little running monologues about repressed tensions over a time and culture that is slipping away, or has slipped away.

I could make a list of these little things, but off the top of my head, the little "atmosphere" things that keep these issues front-and-center are things like the receptionist at Toby's art gallery, doing her nails and treating George like he's not there; Ann's Uncle's little (seemingly) pointless diatribe against London when George goes to Cornwall (I think that got cut from the American version; it definitely appears in the UK version); and Saul Enderby's weird drift, in and out, of an American accent, a nasally "Scotch, anyone". "I'm afraid we aren't worth the candle, these days" George says -- echoing Connie's comment in TTSS about "poor boys, trained to empire . . ." and even Bill Hayden's explanation of why he turned mole . . .

The TV series capture this theme, but never make it explicit. The "heros" are mainly older people, with a vestigal type of honour (Smiley, the General, the Russian woman in Paris), surrounded by a constant theme of shiftlessness or officiousness or vapidness, seen through George's eyes. It's one of my favorite things about the novel: all those little insights/irritations, that you just KNOW are David Cornwall's gripes and irritations! George Smiley rarely vocalizes his irritation, but the novels let us know what's running through his head . . .

Another nice little iteration of the then-and-now theme of a culture in transition: When George and Enderby have their private tete-a-tete about logistics, Smiley says he wants to have Milly McRae (think I have the name right) on his team. After the negotiations are done, Enderby (continuing the theme that he may have difficulties with workplace boundaries) asks "Who is this Milly, someone special?" Smiley answers, curtly: "Just your best housekeeper, and one of your oldest." Unarticulated, George's irritation seems a combination of umbrage that Enderby 1) doesn't even know who the older employee is; 2) therefore has no clue of her value, past and present; 3)wpuld immediately assume a sexual relationship; and 4) can't keep his focus on the matter of Karla. Again, just one of many small details that consistently paint George as in conflict with his society's ethos -- and which paint George as asexual and at least metaphorically impotent, and therefore the geneaological dead-end, so to speak, of a different era and culture.