The ever-reliable Jan Freeman points out on Twitter that the (American) novelist Elinor Lipman used this phrase in an essay published yesterday in the New York Times. Lipman is describing (romantically) breaking up with a British man she had been seeing. “I had acquitted myself in relatively menschy fashion,” she writes. “Done and dusted.”
The Oxford English Dictionary defines the phrase as meaning “completely finished or ready.” Its citations are all from British sources, starting with the British Bee Journal, which had this line in 1953: “All to be done and dusted before the National Honey Show. After this the grand clear up.”
I’m labeling this an “Outlier,” as it is rarely found on this side of the Atlantic. The only other times it’s appeared in the Times in recent years is in the soccer (football) columns of Rob Hughes, an English native. Using it was a nice touch on Lipman’s part, as it echoed the patois of the bloke in question.
And Lipman actually replied to Freeman’s tweet, confirming that this was a favorite phrase of his. “‘And Bob’s your uncle,’ he’d add,” she added.
notoneoffbritishisms.com 
Reading this and recalling some past posts, it occurred to me that a good companion to the OED, NYT, and Google Ngram databases for researching words and phrases here might be a comprehensive database of old movie scripts from the 1920s through mid-century.
‘Done and dusted’ is a common enough expression in the UK. I was more interested in your ‘relatively menschy’ usage quote. That, I guess, is a whole other ball game …
Me too – what on earth does menschy mean?
I assume it means ‘acting like a mensch’ – with mensch meaning good person who behaves well, from the Yiddish. In German ‘Mensch’ just means ‘person’.
Catherine is exactly right. Mensch is a common term in Yiddish and Yiddish-inflected English, with the meaning she gives (though it’s more commonly applied to men than women). “Menschy” is a newer formulation, reflecting the current popularity of -y suffix (discussed by me here: http://www.slate.com/blogs/lexicon_valley/2014/10/17/the_letter_y_makes_words_adjective_y_and_also_more_creative.html)
Ben’s Slate article alerts us to a way of creating adjectives that has once again become popular. Now, if only I could find that reference (also one of Ben’s, perhaps?) seen just within the last few days which indicates that one way to make one’s writing more professional is to go through and remove the adjectives….
Could ‘done and dusted ‘ be likened to ‘all shipshape and Bristol fashion?
Any ideas?
I think that ‘ship-shape’, with or without ‘…and Bristol fashion’ refers to a level of good order or neatness whereas ‘done and dusted’ states that a task is complete.
You’re right: Robert’s your father’s brother and Fanny’s your aunt (to complete the expression)!
Shipshape means in good order. I always heard that Bristol fashion referred to the need for a ship to be able to ready on its bottom at low tide. Bristol is famous for its high tides – 40 feet – so it’s harbour would dry out at low tide. Do shipshape and Bristol fashion is a double compliment, indicating a well maintained and well built vessel.