Task: Question Generation
Input (English): Context : The LB&SCR Belgravia class, were 2-4-0 passenger locomotives designed by William Stroudley of the London Brighton and South Coast Railway (LB&SCR) in 1872 for secondary passenger duties. 
Subject : LB&SCR Belgravia class 
Relation : service entry
Output (English): What year was LB&SCR Belgravia class commissioned?