Ƙirƙirar Class 156 ta kasance mai ra'ayin mazan jiya fiye da Metro Cammell's Class 151 na farko.
Tabbas, wani nau'i mai rikitarwa na jumla shine "Tsarin Class 156 ya kasance mai ra'ayin mazan jiya fiye da Metro Cammell na farko na Class 151, an yi jikin jikin karfe maimakon Aluminum, kuma an tsara zane-zane da ganganci kamar BREL Class 150 don sauƙaƙe karɓar ƙungiyar. "