The BR Class 33 on WSR has a working high-density headlight, and the switch is on the main panel with the marker light switches. But how the heck do you switch the class 37 high-density headlight on? I have skimmed the manual, but didn't see anything (please feel free to whack me if i'm blind).
There's a little switch just next to the Engine Start/Stop buttons on the front panel. Should be directly to the left of the slow speed control.