The subconical galvanized basin you illustrate reminds me of a similar
basin, executed in tinplate, that we found at the Bloomsbury site,
occupied during the late eighteenth century and early nineteenth
century. Patterns for identical tin basins can still be found in the
Audel manual commonly used by tinsmiths today.
I suspect that such basins were quite common, but most tinware comes
out of the ground as a mass of crushed, rusted, sheet metal, and the
archaeologists don't bother to consult a tinsmith. Because of this
pervasive tradition of routine indolence, tinware is seriously
under-reported.