E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Billingsgate (London).
Gate = quay, and bellan is to bawl or bellow. This quay is so called from the shouting of the fishermen in trying to attract attention and vend their fish.
1
Thats Billingsgate. Vulgar and coarse, like the manners and language of Billingsgate fish-fags.
2
Parnassus spoke the cant of Billingsgate.
Dryden: Art of Poetry, c. 1.
To talk Billingsgate, i.e. to slang, to scold in a vulgar, coarse style.
3
You are no better than a Billingsgate fish-fag, i.e. you are as rude and ill-mannered as the women of Billingsgate fish-market. The French say Maubert instead of Billingsgate, as Your compliments are like those of the Place Maubert, i.e. no compliments at all, but vulgar dirt-flinging. The Place Maubert has long been noted for its market.