Rear Brake Disk Oddity

Hi all,
can anyone cast any light on the following issue I have on my otherwise great TF.
On quite a few occasions now I have needed to renew my rear disk/ pads  because  the rear nearside inner surface grows rust as though its been left to stand in the rain  .
The other surfaces are ok and I always check the operation of the caliper and sliders for free travel before rebuilding the brakes.
This happens with different disk makes and over a few thousand miles only , is it possible that the inner ( caliper piston side) brake pad is riding off the disk surface and not wiping the disk surface?
thanks
Mike
 

I think there is a problem with the handbrake linkage. The caliper is  mobile but the pad isn't contacting the disc and that seems to me like a setting up problem with the handbrake cable  not allowing the caliper to adjust when it is released.

From experience of doing this wrong, I know that you must make sure that the brake pads have a notch that should align with a recess on the calipers. And it is important after intalling new brake pads to first press the brake pedal a few times to make sure all space between caliper and brake pad has gone, before engaging the hand brake. 
If after installing brake pads you immediately engage the hand brake, the notch- alignment of the pads to the caliber will be lost, and the pad will be skew to the brake disc, therfore less brake power and corroded disks.  
I have had this, and an MG garage told met what went wrong in my DIY installation of the pads. 

thanks you minimax for the reply, I do know about the handbrake linkage needing to be free on both sides and I always check that it is free to move. I have had in the past the case where only one side of the handbrake linkage is working.

thanks tnjk for your reply also, once again I know about the criticality of not moving the handbrake until the brake pedal is pressed..
between both of the replies the answer to my problem seems not to be unique to me .
I wonder if when I replace the disk the next time I should completely remove all the handbrake tension first with the in car adjuster.
It also may be the case that I am not completely winding in the caliper pistons on both sides equally before reassembling the rear brakes , I know about the notch alignment already .
I will then pump the brake pedal to take up the piston slack on both sides ,and then set up the handbrake with the adjuster.
Sounds like a plan
thanks
Mike