Submitted by Jack, who says:

This is an ad for British Overseas Airways Corporation in the old Australian newspaper The Bulletin, September 17, 1947. I found it while digitizing the paper at work!

Transit Maps says:

This is a glorious find, and one that @airlinemaps would certainly be very interested in. Compositionally, the diagram is very interesting, with a dead straight line linking Britain to the Antipodes (somewhat mitigating the fact that the line represents some three days of flying), and some sweeping, elegant curves representing other “branch” routes. The striking angled typography is spoiled a little by the labels for Hong Kong and Shanghai, which look for all the world like they’ve been added at a later date, shoved in wherever they could fit.

The short-range hopping required for international passenger flight back in 1947 is clearly illustrated by the number of cities called at on the way – there are 15 stops between Sydney and Britain! The other major point of interest is some of the old place names, many of which have been changed over the course of time: Rangoon/Yangon, Salisbury/Harare, Calcutta/Kolkata, etc.