Below are the names and numbers of the steam locomotives that comprised the LNER Gresley Classes A1 and A3, that ran on the Great Northern (GNR) and latterly the London and North Eastern Railway network. They represented Nigel Gresley 's attempt to standardise steam design.

The London and North Eastern Railway Gresley Classes A1 and A3 were 4-6-2 "Pacific" steam locomotives designed by Nigel Gresley for passenger work. They were initially intended for use on the Great Northern Railway (GNR), but became a standard design on the London and North Eastern Railway after the amalgamation of 1923.

Class: LNER A0 Pacific Prototype. Built: 1922, Doncaster Works. Arrived on Sodor: 1923. Current Age (2015): 94. Shed Allocation: Tidmouth

The LNER A1 and A3 Gresley Pacifics. Gresley is most famous for his LNER Pacifics. Although they reached their peak with the streamlined A4s, this famous line of 'racehorses' began with the A1 Pacifics. The first two A1 Pacifics were built in the twilight years of the Great Northern Railway (GNR) and entered service in 1922.

LNER 4-6-2 Pacific Locomotives. The LNER's Express Pacific designs were probably the most famous of the LNER locomotives. Even today, two of these engines (No. 4472 Flying Scotsman and No. 4468 Mallard) rank amongst the most famous steam locomotives ever built. Although the first locos emerged just before the Grouping, it was the LNER that ...

In 1923, the LNER inherited four pacifics, to two classes each consisting of two locomotives, one class from either of two of its constituents, the Great Northern Railway (GNR) and the North Eastern Railway (NER). The Great Northern Pacifics, were of GNR Class A1, designed by Nigel Gresley and numbered 1470/1.

This section of the LNER Encyclopedia describes all of the locomotive classes to serve with the LNER. The LNER would often denote major modifications with a slash. E.g. B16/2 is a modified B16. Occasionally such modifications would be so substantial that a completely new class number would be given (eg. an A3 is a modified A1).

Jeremy was built in Doncaster in 1922 as one of the three prototypes of the LNER A1/A3 Class known as the A0, which included modifications such as a larger boiler. The other two were Boris and Gordon. The following year in 1923, all three A0s has passed most tests and were ready to head to their new homes.

Jay was built at Doncaster on April 29th 1924 as an A0/A3. Jay is based on the LNER's A1/A3 Class of 4-6-2 Pacifics.

The London and North Eastern Railway LNER Gresley Classes A1 and A3 locomotives represented two distinct stages in the history of the British 4-6-2 "Pacific" steam locomotives designed by Nigel Gresley.