The rolling stock situation at the end of SWT’s days would have been quite different if the 458 5-car extension and associated 456 transfer had never happened. The original ITT for extra stock, (which eventually resulted after a few year’s delay in the lash-up we got), was for 120-180 vehicles in 5 car formation to be compatible with the Desiro fleet.
If they’d received what was tendered for in early 2009, the next order in sequence that became the 707s, would most likely have been for similar stock, and we’d possibly just be looking at 455 replacement now...