Green’s Dictionary of Slang

(Aus.) a general term of dismissal, abuse, rubbish, nonsense, anything unimpressive.

1904		Sydney Sportsman (Surry Hills, NSW) 17 Feb. 1/7: A lot of dopuble event backers fell in the bovril badly at Kensington [race track] last week.
1912		Sport (Adelaide) 1 June 10/4: They Say [...] That ‘Captain Percy,’ the bovril man [...] was seen popping the question to Lucy.
1937		H.J. Oliver in Bulletin of the Aus. Eng. Association July in Partridge DSUE (1984) 125/2: A few years ago most young men here [in Sydney] said ‘Bovril’ whenever they found anything unimpressive, and University students certainly made good use of the song, ‘It all sounds like Bovril to me.’.
1955		N. Pulliam I Travelled a Lonely Land (1957) 33: The Aussie has no hesitancy about giving this ‘bloody socialistic Bovril’ a good daily damning.