As above
Other points to consider are that while towing trailers are prone to start swaying. Discovery 4, Range Rover and Range Rover Sport are fitted with Trailer Stability Assist, which automatically detects the presence of a trailer. Once 60km/h is reached, the sensors monitor the behaviour of the trailer. Should any swaying or oscillations occur, the system uses selective braking of the appropriate wheels to help correct

http://theexperience.ning.com/page/land-rover-and-trailer-towing p****d off with a Digital Keyboard Warrior

From what I can see, the TSA seems to be mentioned from MY13 on, this would fit with the fact that this is when the new BCM (body control module) was fitted, in line with other LR products.
It is possible that it is not available on pre facelift vehicles.

Definitely mentioned in the MY13 brochure, here's a quote from it:

Quote:

STABILITY CONTROL SYSTEMS. Freelander 2 comes with a host of stability control systems as standard, designed to
enhance traction by reducing engine torque and applying a unique braking force to each individual wheel where driving
conditions dictate. They include: Anti-lock Braking System (ABS), Electronic Brake-force Distribution (EBD), Emergency
Brake Assist (EBA), Cornering Brake Control (CBC), Electronic Traction Control (ETC), Dynamic Stability Control (DSC),
Roll Stability Control (RSC) and Trailer Stability Assist (TSA)