Shotgun wedding

[Jonathon Green]

Can anyone help?

The first citation I have been able to find for the term shotgun wedding
(var. shotgun marriage) is

1927 Sinclair Lewis _Elmer Gantry_ 156: There were, in those parts and those
days, not infrequent ceremonies known as 'shotgun weddings'

'Those days' refer to the context of Lewis' story: the 1900s. I have yet to
find any earlier citation than this and the (online) OED has the same first
cite.

I am currently reading Miles Franklin's _All That Swagger_, set in Australia
from appx. 1830-70. Franklin uses a great deal of Australian slang,
purportedly that of the story's period. On p.163 of the UK 1st edn. (1936) I
find\:

He paid his debts and withdrew to prepare for a shotgun marriage.

This is supposed to refer to a date around 1860. Sidney Baker, in his
_Australian Language_ (1945) notes Franklin's book as a good source of
Australian slang, but warns that there it contains 'anachronisms'. He does
not, unfortunately specify 'shotgun weding' among them.

Does anyone know of a pre-1927 citation or indeed usage prior to Lewis'
fictional 1900s? Or should I assume, as at the moment I do, that this is
indeed one of Franklin's anachronisms?

Jonathon Green