The excellent ianVisits website about London and travel reports that Southeastern have issued a notice to train manufacturers to buy a new fleet of trains, to go into service in late 2027. It seems that these are to replace the aging “Networkers” used for suburban services and also the services to Tunbridge Wells.
Apparently the specification calls for both toilets and air conditioning – although it’s not clear whether the new trains will have proper seats or just the “covered boards” that were used for the new Thameslink trains.