Bandboy (also expressed as band boy) is a bygone term for a job similar to for what now is known as a "roadie."
Unlike a roadie, the bandboy was more like a personal assistant, or au pair, or butler/dresser for the leader — making sure suits were dry cleaned, shoes shined, and the like.
On foreign tours a local bandboy would translate, find places to eat, change money, buy train tickets, and perform similar tasks.
The role of bandboy was different with every band and had different duties than the more senior road manager, who dealt with promoters, booking agents, contracts, payroll, and catering.
When times got tough financially, road managers or band members themselves often performed bandboy duties.