Most likely they were a commercial travellers, who sold goods, or took orders for goods, on production of samples, generally by calling on the consumers as a representative of his/her firm, and worked usually on a commission basis, or on a small salary and commission. They usually operated in particular districts, displaying samples to prospective buyers in their shops.
In 1850's tramps called themselves travellers, the use of 'traveller' as another name for gypsies dates from about the 1960s.
There are many individuals in lodging-houses who are not regular patterers or professional vagrants, being rather, as they term themselves, ‘travellers’ (or tramps).
MAYHEW "London labour and the London Poor" 1851–61
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