I was thinking of including the Class 466 Networker on Southeastern High Speed Extended. It can be coupled with the Class 465/9 Networker to make 6 car and 10 car train formations on the route. Class 466 units operate in multiple with Class 465s. They were historically used as individual units on rural routes, mainly the Sheerness Line between Sittingbourne and Sheerness, displacing the Class 508/2s which operated on this branch line and on the Bromley North branch between Grove Park and Bromley North. However, owing to their non-compliance with accessibility standards, since 1 January 2021 they may only run coupled to a Class 465. The Class 466s were also used on the Medway Valley Line between Strood, Maidstone West and Tonbridge, and in the leaf fall and winter season of 2011, the Class 466s were doubled up to make 4 car units on the Medway Valley line to help stop the poor adhesion along the line when only a single unit runs. They also ran doubled up or coupled with a Class 465 on the Sheerness Line during the winters of 2009/10 and 2010/11. From the May 2012 timetable changes, Class 375s replaced the Class 466s on the Medway Valley line and from December 2019 on the Sheerness Branch Line. These two-car EMUs are formed of a driving motor carriage (DMOS: Driving Motor Open Standard) and a driving trailer carriage (DTOSL: Driving Trailer Open Standard Lavatory); all on board seating is standard accommodation. A Solid State Traction Converter package controls 3-phase AC Traction motors, which allows for Rheostatic or Regenerative Dynamic braking. Primary braking system is electro-pneumatically actuated disc brakes, which is blended with the Dynamic brakes. Speed Probes on every axle of the unit provide for Wheel Slip/Slide Protection. A solid-state Auxiliary Converter provides 110 V DC and 240 V AC supplies; this is the source of the loud buzzing noise which can be heard when the train is stationary. The Aux Converter is located on the driving trailer, along with the toilet. The units use air-operated sliding plug doors. Each of these units is formed of two coaches that have dimensions of 20.89 m × 2.81 m (68 ft 6 in × 9 ft 3 in) and a top speed of 75 mph (121 km/h).
Another basically rework of a train in the same route - jokes of of way this would be an amazing idea.
This would be better in its own route when it didn't need to run coupled with the 465. We already have a 465 and I don't think this would really add much more to sehs and would have better value in its own route and then layer/sub into sehs maybe?