Green’s Dictionary of Slang

ruffler n.

also ruffeler, rufflar, rufler
[SE ruffle it, to swagger; it is linked to the idea of a bird ruffling up its feathers]

[mid-16C–mid-19C] (UK Und.) a villain, of the ‘first rank of canters’, who posed as a discharged soldier (and might indeed have been one, though equally likely might have been a former servant), but actually worked as an itinerant; thus ruffling adj.