Tom, I had to go look up the NRCS description of Luton.  Here's a link:  https://soilseries.sc.egov.usda.gov/OSD_Docs/L/LUTON.html

Oftentimes, when describing a soil, competing soils will be listed, and how they are different than the subject.  Luton has NO soil types like it!

A level horizon - 40 to 75 percent clay.

And I thought Wabash or Aholt was bad!