If your car has "power brakes", that's it. ABS pulses the brake fluid to each wheel cylinder, as signaled by wheel speed sensors, to prevent an individual brake from locking up - a skidding tire has less traction than a pulsed brake application. Stability Control works with ABS to try and maintain intended car direction. There is no "booster pump" other than the original power brake booster diaphragm itself.
Get to a deserted country road, accelerate to 50 mph and do a real panic stop - brake pedal through the firewall. See/feel what happens.
If your UK car has RHD, you probably have the HydroBoost braking system because the LHD brake booster/master cylinder might not fit over on the right side. (Now, that's true for my series of Seville - your "STS" RWD may be different.)