I had front wheel tracking adjusted and new tires fitted under a year ago. I have just replaced the front tires due to excessive/uneven wear. I need to replace one of the steering rack gaiters so I may as well check the tracking while I'm at it.

I am assuming it is the tracking as wheels are balanced, rotors, pads and shocks have all been replaced in past year (or is there something else I should check?)

There's twice as much wear on the left tire than the right and the wear was on the inside (tire was as smooth as a racing slick after 13,000 miles) Does this mean that the tie rod end on the left is out? Or could I adjust the right to compensate?. Right tire had less wear but was still uneven (on inside too).

You shouldn't adjust anything on your right side on a blind guess at what might be the problem, or else you'll have both sides wearing your treads off too quickly.

Make sure your bushings, tie rod ends, and ball joints are all good. If they're good you should just take it in for another alignment.