Familiar facial expressions

I have been reminded of a passage from Brideshead Revisited on several occasions recently and thought it would be a good idea to track it down.

Towards the end of that summer term I received the last visit and
Grand Remonstrance of my cousin Jasper. I was just free of the schools, having taken the last paper of History Previous on the afternoon before; Jasper's subfusc suit and white tie proclaimed him still in the thick of it; he had,too, the exhausted but resentful air of one who fears he has failed to do himself full justice on the subject of Pindar's Orphism. Duty alone had brought him to my rooms that afternoon, at great inconvenience to himself and, as it happened, to me, who, when he caught me in the door, was on my way to make final arrangements about a dinner I was giving that evening.

It is assumed that we are all familiar with this particular facial expression.

On a related note: in IGL's entry for the word θυμβροφάγος (cf. Aristophanes, Acharnians 254), we read "to look as if one had eaten savory, make a savory or (as we might say) a verjuice face".

H.G. Liddell might have described such an expression in this way, but I doubt that such a description would be clear nowadays.