The Class 341 was to be operated on the original version of the Crossrail project. The project for these units never went ahead. A mock-up unit demonstrating the design of the train was built in 1991. One version of Class 341 would have had it forming part of the Networker family. The specifications drawn up for the Class 341 have since been used as a base for laying down specifications for the new Class 345 units to be built to run on Crossrail once it begins operations in 2017.
The Class 342 was planned to be utilised in operating domestic services on the CTRL high speed line between London and the Kent coast. These services were abandoned before the line was opened and the trains never got beyond the proposal stage. The CTRL, or High Speed 1 as it is now known, did not finally open until 2007 and domestic services began running in 2009, operated by Southeastern using Class 395 high speed trains.