No Worries

[Jonathon Green]

It does indeed appear to be an Australianism. G.A. Wilkes, in the Dict.
Australian Colloqualisms (3 edn.), has a citation for 'no worries' dated
1966; the Australian National Dictionary has one in 1969. I have found one,
in the 'Barry McKenzie' cartoon strip - running in the UK satirical magazine
Private Eye from 1963-74. Unfortunately my cite comes from a 'collected'
version of the strip, so its precise date is hard to pin down but (based on
the book's overall pagination) I would put it, again, around the
mid-Sixties.

Jonathon Green