Reading to London Waterloo via Richmond would be a great line to add as it is a pleasant route with trains running on it that are not in TS right now. With this route you could have the Original 458 or the 458/5. Other choices for the routes trains could be the 707 or the 701 to give it a really modern and up to date feel.
Great Idea for this route to come into the game and DTG would Earn more money and the route is part of the south western Division of Network southeast buisness