The Class 187 is the AC3 version of Bombardier's TRAXX, introduced in 2012 as the successor to Classes 145, 146, 185, 186. The 187 has a modified cab design but the most significant change is the option for a small "last mile" diesel engine to be fitted, allowing it to operate away from the wires.
Unlike its predecessors which were classified differently depending on whether they were passenger or freight locos (different bogies) and whether they were 15kV AC only, 15/25kV AC or 4-voltage, Class 187 covers all the different variants in a single class.