Many readers will perhaps have heard the music hall song “My Old Man (Said Follow the Van)” by Fred W. Leigh and Charles Collins and made popular just after The Great War by singer Marie Lloyd (who never actually recorded it). The song contains the lyric:
I walked behind wiv me old cock linnet.
The “cock linnet” mentioned is the male of the passerine bird species Linaria cannabina (previously known as Carduelis cannabina until DNA analysis separated it from the genus that carries the likes of the Goldfinch, Carduelis carduelis). Captive songbirds were a favourite of all classes for centuries and certainly at the time of the writing of this song may well have been a favoured pet of a Cockney housewife.
The male of the species takes on a rather suggestive blush to its breast when in its mating plumage at the height of spring. The allusion to the male member being rather obvious and commented upon in several sources including the excellent “The Red Canary: The Story of the First Genetically Engineered Animal” by Tim Birkhead: