Over the course of the franchise, a number of the older Class 156 and Class 158 trains were transferred away to other operators including Wales & Borders and One. This was balanced by the acquisition of additional Turbostar trains no longer required by sister company Midland Mainline as well as additional Class 150 and Class 158 units made surplus by other operators. Over the years, both Class 150 and 158 trains were shuffled between two and three carriage formations to meet changing needs.