Was a BBC program you can catch up with here for a few more days.
I did something unusual for me and watched it to unwind the other evening - it is almost unknown for me to watch TV, even through iPlayer. Chris was in the room at the same time, and we got talking about guitar music and riffs, how they make you feel excited, energised, a little bit naughty and rebellious. That may be good or bad (or both) depending on theology and world-view.
Then it got to the Smiths and Johnny Marr.
They talked about how he refused to listen or be influenced by metal or rock, returning to a clean, bright tone (I know he also tuned guitars above concert pitch to make them sparkle and discourage string bends). After hearing him play a bit, Chris made the observation that he deliberately took away all the things that made guitar sound good, exciting and fun, then used what was left. That pretty much covered it. For those who care, there was also an amusing bit where they were talking about Rickenbacker jangle while the guitar actually played was a telecaster, but I guess it's hard to find music journos with a background in music.