The
Banana Joe's MkIIIC (former Jim Mathews Racing) is equipped with a Megaline
sequential paddle-shift mechanism located on the steering wheel.
The paddle shifters control a pneumatic unit which actuates the gear change. 
The
pneumatic unit is located behind the engine on the right hand side of the
engine bay. Based on input from the paddle shifter, it sends the
air charge that then initiates the correct gear change. 
This
valve on the gearbox actually completes the change.