Wiktionary
Etymology 1 n. 1 (context historical cant English) A thief who steals the copper siding from the bottoms of vessels, particularly in or along the Thames. 2 (context chiefly historical English) A scavenger of valuables lost in the sewers, particularly those of London during the Victorian age. Etymology 2
a. (en-comparative of: tosh)
Wikipedia
A tosher is someone who scavenges in the sewers, a sewer-hunter, especially in London during the Victorian era. The word tosher was also used to describe the thieves who stripped valuable copper from the hulls of ships moored along the Thames. The related slang term "tosh" referred to valuables thus collected, both are of unknown origin.
Usage examples of "tosher".
No wonder Sutton, whose father had been a tosher and knew all the waterways large and small, was now frightened by the vast steam engines that shook the ground, and by the knowledge that men were digging, shoveling, and moving earth, disturbing what was settled.
They were dressed in the usual tosher gear: high rubber boots, hat, and harness.
One day, in a week, or a month, some tosher would find their bones, picked clean by rats.
Then Crow went up again with bodies, and Monk found himself beside a barrel-chested navvy and a tosher with a broken front tooth that made his breath whistle as he heaved and dug.
They were a devoted family and Leslie and Basil were said to be particularly concerned when their brother Peter was seen by several witnesses kneeling in the street outside a pub called the Old Justice beside the blood-stained body of an East End character known as Tosher MacBride.
I came out of the Old Justice pub that night I see Tosher on the pavement and Petey Delgardo was kneeling beside him.
Mr Delgardo let go of Tosher, of that good man Mr MacBride, ran to his car and got into it ?
So that rainy night, outside the Old Justice pub in Stepney, Mr X waited for Tosher, waited with this knife and, when he saw his unfaithful servant come out of the shadows, he stabbed.
And she lost no time in composing a brief letter to Sutton, telling him of her need to learn more from the toshers who knew the old system best.
He could speak to toshers, who combed the sewers for lost valuables, or to gangers, who led the men who cleared the worst buildups of detritus and silt that blocked the narrower channels.
I thought it was to bribe a bunch of ruffians to see off some of the toshers who were giving us a hard time and spreading rumors about uncharted underground rivers and scaring the hell out of some of the navvies.
Jenny, poor Mary Havilland, the navvies who carried out his orders to fight the toshers now and then.
As Sixsmith said, I wanted to hire someone to prevent the unrest among navvies regarding safety, and stop the toshers, whose territories were disappearing, from becoming violent and disrupting the excavations.
Argyll told me it was to hire men to keep the toshers and navvies from disrupting the work.
We discussed the problem of the toshers in particular, and I told him a little more about it.