The pressure of the brake fluid activates this switch, which screws into the banjo fitting on the front subframe on the right side. This system was used in Classic Mins up until 1976, when the switch was moved to the pedal. It was used in Spridgets through 1967. Genuine Lucas

The vast majority of the cars we deal with have brake lights that are activated by sensing the fluid pressure in the brake lines. A "Tee" is usually placed in a corner with this pressure switch attached. If your brake lights don't work this could be your problem. The late blade type will also work in a Sprite , MG Midget , and Morris Minor . The early version of this with screw terminals can be replaced by this push-on terminal type! screw type is CBS127