The class 66, introduced in 1998, is now the most numerous in operation on Britain's railways. Like the class 59, it was built in the USA by GM-EMD and is a development of the class 59. Because of this, they share some design details and look outwardly similar.
https://en.wikipedia.org/wiki/British_Rail_Class_66
Current operators include GBRf, DBC, DRS, Freightliner & Colas Rail
Tony