The Collaborative International Dictionary of English v.0.48:
Sidesman \Sides"man\, n.; pl. Sidesmen. 1. A party man; a partisan. --Milton. [1913 Webster] 2. An assistant to the churchwarden; a questman. [1913 Webster]WordNet (r) 3.0 (2006):
sidesman n 1: (Church of England) an assistant to the churchwarden; collects offerings of money in the church