Green’s Dictionary of Slang

a middle-man, esp. at Billingsgate fish market; thus bummareeing n., working as a bummaree.

1786		Report of Committee of City of London on Price of Provisions 31: The bomarees will buy up half the fish the Salesmen have, and sell to the fishmongers [F&H].
1859		G.A. Sala Twice Round the Clock 21: The process of bumbareeing is very simple. It consists in buying as largely as your means will afford of an auctioneer, hiring a stall for sixpence, and retailing the fish at a swinging profit.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 64/2: The market opens at four, but for the first two or three hours, it is attended solely by the regular fishmongers and ‘bummarees’ who have the pick of the best there. [Ibid.] 67/2: I asked several parties as to the origin of the word ‘bummaree,’ [...] ‘Why, bless your soul, sir,’ said one Billingsgate labourer, ‘there always was bummarees, and there always will be; just as Jack there is a “rough,” and I’m a blessed “bobber”.’ One man assured me it was a French name; another that it was Dutch. A fishmonger, to whom I was indebted for information, told me he thought that the bummaree was originally a bum-boat man, who purchased of the wind-bound smacks at Gravesend or the Nore, and sent the fish up rapidly to the market by land.
1864		Hotten Dict. of Modern Sl. etc. 89: bummarees jobbers or speculators on the Fish-Exchange at Billingsgate market. One man at this celebrated fish market declared it was a French name (beaumaris, gros poisson, espèce de squale); another, that it was Dutch; whilst a more intelligent salesman believed bummaree was originally a bum-boat-man, who purchased of the wind-bound smacks at Gravesend or the Nore, and sent the fish rapidly to the market by land. The bummarees are accused of many trade tricks. One of them is to blow up cod-fish with a pipe until they look double their actual size. Of course when the fish come to table they are flabby, sunken, and half dwindled away.
1876		J. Greenwood Low-Life Deeps 80: Billingsgate is the theatre of our observation of the Bummaree.
1906		O.C. Malvery Soul Market 165: Fish is brought up to Billingsgate [...] Their principal customers are the class known as ‘bummarees’.