Interesting comment Paul, and I must admit that I have been known to cringe when visiting US artists have felt compelled to mention "Northern Soul" when playing at events/venues that are anything but "Northern Soul"!!
In contrast I saw Bettye LaVette perform in London about three times in the 2005/10 period and she very much stuck to her preferred bluesy/ballad material. My understanding is that when she appeared at "Northern Soul" venues "Up North" she would follow the advice of the promoters and put on a very different show and include more upbeat '60s material like "Only Your Love Can Save Me" and "I'm Just A Fool For You", songs that I never heard her sing in London. If that is true then at least one "Soul" singer understood what was going on.
Roger