Green’s Dictionary of Slang

daddler n.²

a farthing.

1900		Marvel 21 Dec. 16: Rewarded er sivility wiv a daddler in mistaik for a brase butten.
1911		J.W. Horsley Memoirs of a ‘Sky Pilot’ 254: Other [words] were new to me, such as [...] ‘dadla’ or ‘fadger’ for a farthing.
1953		J. Franklyn Cockney 315: Before 1914, when a farthing had considerable purchasing power, its slang title was a daddler.
1976		(ref. to 1930s) R. Barnes Coronation Cups and Jam Jars 70: You don’t see the farthing any more now, but we used to know it as a dadler.
1999		G. O’Neill My East End (2000) 79: My father’s generation of East Enders – he was born in 1919 – do not speak the dull, uniform, flat-vowelled Estuary English [...] He will still use what is essentially Victorian idiom – phrases such as ‘daddler mooey’ and ‘fard’n face’.