Last week, DRS officially announced their order for 10 additional Class 68 locomotives (68016-68025) on top of the 15 that are currently being delivered. The main driver for the order is that performance testing of the locomotive has exceeded expectations.
Of course, this news was not completely new. Back in April, at the Multimodal 2014 trade fair in Birmingham, DRS already stated it would order 10 more locomotives.
Related sections:
Class 68: Beacon Rail