Cheers to the British

On this Independence Day, having just returned from England, it seems right to comment on yet another little way American English has differentiated itself from British English, or vice versa.

When I returned the sunglasses a man was about to leave behind on the Underground (having to work hard to get his attention to do so), he was quite pleased and answered, "Cheers!" That got me listening for other uses of the word, which the English-to-American Dictionary defines this way:

informal substitute for “thank you.” Somehow derived from its use as an all-purpose toast.

The Best of British holds that "Cheers" is a bit more tricky:

This word is obviously used when drinking with friends. However, it also has other colloquial meanings. For example when saying goodbye you could say "cheers", or "cheers then". It also means thank you. Americans could use it in English pubs, but should avoid the other situations as it sounds wrong with an American accent. Sorry!

Lynne Guist at Separated by a Common Language has the most thorough discussion, of course. She has a lot more to say about the use of "thank you" in three different languages, and remarks:

Cheers is interesting because it is so flexible. In AmE, it is simply used as a salutation in drinking (or sometimes with a mimed glass in hand, as a means of congratulations). In BrE it has this use, but is also used to mean 'thank you', 'goodbye' or 'thanks and goodbye'.

In my own experience, especially in commercial transactions, I came to think of "Cheers" as signaling this feeling:

This has been all quite nice, and I'm glad to have interacted with you, but now we're done.