The prototype was rebuilt in 1912 from a member of Class G and a further 170 new locomotives were built between 1912 and 1918 .
It was a superheated version of the LNWR Class G with 8 inch piston valves .
The prototype was rebuilt in 1912 from a member of LNWR Class G   and a further 170 new locomotives were built between 1912 and 1918 .
It was a superheated version of the LNWR Class G with 8 inch piston valves .