Great Northern Railway Classes P & PP
Type and origin Power type Steam Designer {J.C. Park C. Clifford Build date 1892(P) 1896(PP) Total produced 29[a]
Specifications Configuration: ​  • Whyte 4-4-0 Gauge 5 ft 3 in (1,600 mm) Driver dia. 6 ft 7 in (2,007 mm) 5 ft 7 in (1,702 mm) Boiler pressure 175 lbf/in2 (1,206.58 kPa) Cylinders Two, inside Cylinder size 17 in × 24 in (430 mm × 610 mm){P) 18 in × 24 in (460 mm × 610 mm)(PP) Train heating steam
Performance figures Tractive effort 13,840 lbf (61.56 kN)−15,340 lbf (68.24 kN)
Career Operators GNR(I) → UTA → CIÉ Number in class 29 Numbers 12, 25, 42–46, 50, 70–71, 74–77, 106–107, 129
[1]

Great Northern Railway Class P were two sets of 4-4-0 locomotives for the Great Northern Railway of Ireland (GNRI) introduced from 1892 by locomotive superintendent J.C. Park; four having 6 ft 7 in (2.01 m) driving wheels and eight having 5 ft 7 in (1.70 m) driving wheels. Park was succeeded by Charles Clifford who constructed 17 broadly similar locomotives from 1896 with 6 ft 7 in (2.01 m) driving wheels; these were designated Class PP.^[2] The last PP class survived until 1963.^[3]