Updated: 10/1/2024
As far as I am aware the Holcroft-Anderson recompression locomotive was the first and only tested attempt to integrate a powerplant mechanical vapor recompression system into a steam locomotive. Although the life of the experimental locomotive was cut short, it's limited success convinced Harold Holcroft that further development of the system should be pursued. The original inventor H. P. H. Anderson had died in 1938, the Steam Heat Conservation Co. dissolved in 1939, and the patent rights had been allowed to expire. This left Holcroft as the only individual with the knowledge necessary to recreate the system. When in discussions with Oliver Bulleid between 1942-1944 Holcroft brought the recompression system experiments to his attention. Oliver Bulleid judged the system as practical, baring the draft inducing fan, and authorized Holcroft to begin preliminary design work on an improved recompression system to be fitted to the new Pacifics.
The details of the design work done are documented on pages 168-173 of Locomotive Adventure Vol. 1.