GNRI Class PG  Great Northern Railway Classes PG, QG, QLG and QNG were a series of 0-6-0 freight locomotives introduced from 1899 by Charles Clifford. The PG class was introduced in December 1899 by Charles Clifford with driving wheels and cylinders. The QG's introduced in 1904 were longer than the PG with cylinders weighed in 2 tons heavier. The key changed with the QLG class introduced in 1906 was a wide boiler.