▁them ▁passed ▁into ▁British ▁Rail ways ▁ownership ▁and ▁they ▁were ▁number ed ▁ 5 5 1 1 9 - 5 5 1 4 6 ▁( with ▁g aps ). ▁ ▁Later ▁versions ▁ ▁In ▁ 1 9 2 2 ▁Pick ers g ill ▁introduced ▁the ▁ 4 3 1 ▁Class ▁with ▁larger ▁cyl ind ers ▁and ▁cast - ir on ▁front ▁buffer ▁beam ▁for ▁bank ing . ▁ ▁The ▁idea ▁was , ▁pres umably , ▁to ▁move ▁the ▁centre ▁of ▁gravity ▁for wards ▁and ▁put ▁more ▁weight ▁on ▁the ▁driving ▁whe els . ▁ ▁However , ▁it ▁seems ▁strange ▁to ▁use ▁a ▁large - w he e led ▁ 0 - 4 - 4 T ▁( r ather ▁than ▁a ▁small - w he e led ▁ 0 - 6 - 0 T ) ▁for ▁bank ing . ▁ ▁The ▁ 4 3 1 ▁Class ▁was ▁number ed ▁ 4 3 1 – 4 3 4 ▁by ▁the ▁C aled onian , ▁ 1 5 2 3 7 – 1 5 2 4 0 ▁by ▁the ▁L MS , ▁and ▁ 5 5 2 3 7 – 5 5 2 4 0 ▁by ▁British ▁Rail ways . ▁ ▁In ▁ 1 9 2 5 ▁the ▁L MS ▁introduced ▁their ▁own ▁version ▁of ▁the ▁ 4 3 9 ▁Class ▁and ▁these ▁were ▁number ed ▁ 5 5 2 6 0 - 5 5 2 6 9 ▁by ▁British ▁Rail ways . ▁ ▁In ▁the ▁ 4 3 1 ▁and ▁L MS ▁classes , ▁the