'Sooner than' what?

 A small point, but one that bothers me rather more than somewhat (an  expression I first heard my mother using ...

<autobiographical-note>
(the context was 'that little madam gets up my nose rather more than somewhat' – referring to one of her daughters;  no names, no packdrill, besides, de mortuis... whoops, me and my big mouth), but she probably picked it up among the hip talk of the 1930s, or maybe she was quoting Damon Runyon)
</autobiographical-note>

...) is the meaninglessly abbreviated expression 'sooner than later'. It's not complicated: the word 'rather' contrasts two possibilities: doing something sooner or doing it later; the former is preferable. The word 'rather' is the  WHOLE POINT of the expression 'sooner rather than later', and dropping the 'rather' is cutting beyond the bone. I'm all for cutting out dead wood in over wordy expressions, but this is not dead; it's structural – load-bearing.

When I first heard this, I blamed the Americans (as is often the way, usually mistakenly), possibly because the first time I noticed it was in a Letter from America (which dates it: probably around the turn of the millennium...)

<pedantic-sideswipe>
(two ns, please, unless you've discovered a new heavy metal [with atomic number 1000])
</pedantic-sideswipe>

... as the last one was broadcast in February 2004.  My guess is that the relevant broadcast was in the mid-late '90s.

The balance in the British National Corpus is strongly in favour...

<you-know-thats-not-what-I-mean>

<tangent>
And the missing apostrophe's deliberate. I know the pseudo-code compiler doesn't exist, but if it did then ' would be (as they say) a 'reserved character'. (To test this, try to write a Twitter [or whatever your poison is] hashtag that includes '. The highlighting gets switched off at the '...

<inline-ps> 

– it's a 'reserved character'; that is, it slips out of your context, and starts talking to the computer. It's 'reserved' in the sense that it has a special function and shouldn't be used for anything else: Computer says NO.

<inline-ps>

...).
</tangent>

(not that a corpus can express a preference; it just records what happens [in this case, what has been written])
</you-know-thats-not-what-I-mean>

...of  'sooner rather than later' 65/6; that is, the shorter (that is,  content-free) version is a bit less than 1% as common.

Meanwhile in the Corpus of Contemporary American English (a much bigger corpus) the preponderance is 1031/424. The shortened version is less uncommon, but is still much less than half as common.

So can it be called an 'Americanism'? I think the answer is more nuanced than that; we need (though 'need' is a strong way of putting it) a more granular corpus. As Alistair Cooke was based (at the time when I heard him use the LAMENTABLE short form)  in New York, it seems to me worth considering that the preference for this ABERRATION (sorry, the small caps are like Dr Strangelove's right arm – they just spring up unbidden from time to time) is peculiar to New England. But the only granular corpus I've found is Corpus of Historical American English (the wrong sort of grains– though possibly informative):

So when Alistair Cooke first disturbed my linguistic platitude (that's a new meaning I've just invented, referring to an unruffled plate-like surface) he was toying with an essentially 21st-century neologism: of the 30 (I make it 29, but who's counting [apart from me, obv.]?) more than half were written since the turn of the millennium; so the offending Letter to America was written during the very early stirrings of an UNFORTUNATE development (OK, it had been attested since the late 19th century, but ⅔ of the total were recorded in the 21st).

Enough of this. There's biomass crying out for destruction in the back garden, not to mention words/notes to learn for Saturday week's concert:

b

Update 2023.06.27.12:05 – Added <inline-ps />