Before the telegraph they used to do things wirelessly: https://www.brunningandprice.co.uk/_downloads/telegraph/tele...
(Not quite London to Australia though...)
In the late-1700s/early-1800s the Admiralty Telegraph was used to relay messages between London and Portsmouth (70 odd miles apart) using a semaphore type system with repeater stations every 10 miles or so.
Unlike normal rubber, it is a type of thermoplastic and it's a popular organic plastic before the petroleum based modern plastic become pervasive [2].
[1] The legacy of undersea cables:
https://blog.sciencemuseumgroup.org.uk/the-legacy-of-underse...
[2] Gutta-percha:
jphoward•1h ago
And one of the old cable huts still exists: https://en.wikipedia.org/wiki/Pacific_Cable_Station
alexfoo•11m ago
(There's also the https://en.wikipedia.org/wiki/Minack_Theatre built into the cliff face nearby.)
(I've been to the theatre a number of times but never convinced my in-laws to visit the Telegraph Museum.)