……..
Most cars will make a lot of warning noises if you do pull on the EPB when in motion. And most I've driven require the switch to be held in the apply position, and will immediately release when the switch is release when applied with car moving, being a different way of working than when the car is at standstill.
……
Well well, I wasn’t aware of that. Every day’s a school day.

I’ve just watched a video clip of this very thing. Apparently, when the EPB is applied momentarily whilst driving, the vehicle uses the ABS function to slow down the vehicle safely, but then automatically releases it, assuming that the driver is a pillock and did it in error.

As TB said, if you hold the EPB, the vehicle assumes that it’s intentional and safely brings the speed down at a faster rate.
So to conclude, it wasn’t my lightening reaction which deactivated the EPB, it was the car.

And the clunk that I felt, was the auto box showing its displeasure at being stopped without prior warning. I recognise that clunk from when I did a rapid change of direction using the handbrake in my Omega. It had a different type of auto box but that was equally unhappy with my style of driving as well.
