Green’s Dictionary of Slang

daddler n.2

also dadla, dadler
[? SE tiddler, something very small]

a farthing.

[UK]Marvel 21 Dec. 16: Rewarded er sivility wiv a daddler in mistaik for a brase butten.
[UK]J.W. Horsley Memoirs of a ‘Sky Pilot’ 254: Other [words] were new to me, such as [...] ‘dadla’ or ‘fadger’ for a farthing.
[UK]J. Franklyn Cockney 315: Before 1914, when a farthing had considerable purchasing power, its slang title was a daddler.
[UK] (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.
[UK]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’.