Just a guess, but uneven wear may be due to sticking pistons in the calipers (to some degree, most cars with floating "American-style" calipers have some uneven wear....but fixed-caliper disk brakes as on a TR6 should have pretty even wear).
Part of this may be caused by the vehicle sitting around for a period of time (I go through a process of "unsticking" the calipers on my street bike every Spring).
Anyway, one method that might free-up sticky calipers would involve the following (this assumes you do not have floating calipers...older Brit cars generally do not):
1. remove both brake pads on one side
2. have someone *slowly* press down on the brake pedal until the pistons start to "come out" of the calipers....don't let them come out more than 1/2"
3.If one of the two pistons in the caliper doesn't come out, install the brake pad on the opposite-side piston (you'll have to compress it back into the caliper using a C-clamp or caliper tool)
4. Again, apply carefull pressure to the brake pedal.....this should force out the stuck piston.
5. Repeat this process four or five times (forcing the piston out using pedal pressure and then pressing it back in). This usually "frees up" the piston.
6. Repeat the process on the opposite side caliper.
If the caliper remains sticky or is leaking, replacement with a rebuilt or new caliper is your only choice (I haven't seen a lot of success with "backyard rebuilt" calipers).
BTW, I use a wooden carpenters glue clamp (instead of a C-clamp) to compress the caliper. Avoid using a big screwdriver (or similar) unless you're desperate.
Here's another idea on Triumph calipers:
https://www.vtr.org/maintain/brake-conversion.html