ACMS, as mentioned before that was the Grimes light.
Before the Sea King, all RN helicopters had red instrument lighting but the SK came with adjustable white lighting throughout the cockpit. True to military fashion, the standby compass, the E2B, was remustered as the E2C when the colour was changed!
Regardless, the carriers went to red lighting throughout for night flying and we continued to stumble around in the gloom until we got airborne and returned to normality. Being young and bulletproof it never seemed much of an issue, especially when returning to Mother in darken ship state only to see her from 25 miles away as an F4K lit up the reheat on the cat!