This would be a good commuter route because tsw doesn’t have much uk, electricified routes yet, and the lines are a good distance. Class 321’s and 720’s operate on the line Plus tfl/ cross rail services (soon)- class 710’s and 315’s https://en.m.wikipedia.org/wiki/Crouch_Valley_line https://en.m.wikipedia.org/wiki/Shenfield–Southend_line https://en.m.wikipedia.org/wiki/Great_Eastern_Main_Line