A fourth batch of Sentinel models were announced in July 2017. These arrived in November 2017 and all sold out by October 2019!
The Sentinel tooling is exclusive to Model Rail. Featuring an eight pin DCC Decoder socket and Dapol "Supercreep" motor, the tooling caters for detail differences for LNER Y1 and Y3 variants, two different whistle positions and twin or single injectors.
Each version was limited to 250 pieces.