Still on the theme of daft or stupid, as in ‘Don’t be a duffer’, though not current. It seems to have an additional meaning in Australia: stealing or altering cattle brands. ‘BETTER DROWNED THAN DUFFERS IF NOT DUFFERS WONT DROWN.’
Source: Arthur Ransome, Swallows and Amazons (London: Vintage, 2015 (1930)), p. 3
