Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
The London and North Eastern RailwayClass K5 consisted of a single rebuild of LNER Class K32-6-0 No. 206 (later No. 61863), rebuilt in 1945 by Edward Thompson. The rebuilt locomotive had a new boiler and two, instead of three, cylinders following earlier rebuilds of other Gresley designs. The aim of the rebuilds was to move away from the well established three cylinder policy achieving similar results through higher boiler pressure and two larger cylinders. Easier maintenance and greater availability was the objective.
This locomotive was withdrawn in 1960, and later scrapped.
Sources
Ian Allan ABC of British Railways Locomotives, part 4 (1948 ed.). p. 17.