The origins of the name are somewhat obscure, and may be one of a number of derivations.The basic word is from the Old English adjective Trum which meant firm, which gave the Old English verb Trymman to set in order, from which we get the verb “to trim”, and so the noun a trimmer for someone who trims.
The origins of the noun as a verb probably came from either from the nautical term for someone who managed the course of a boat by “trimming” the sails, or from someone who trimmed hedges or sheep.
This term “A Trimmer” was then corrupted into a term for a woman who scolded her husband and thereby kept him in order, and for people who were out to serve their time and survive in a position of employment irrespective of the fluctuations of those around them, as they would “trim their course” between all parties.
Given that the Trimmer name in this line was particularly common in central Hampshire, it is very likely that the derivation in this case was for someone who trimmed sheep or wool during the Middle Ages.
At some stage leading they left the land for a life in Southwark, which was then part of the Surrey Bank of the Thames South of London, and were working as Chimney Sweeps an occupation that they kept to for nearly 100 years.