This is the wall that runs W-E to the S of the entrance in the SW baulk of WSDB. Its measurements were taken in the approximate center. Originally, the locus captured only the .94 m length of this wall that lay within the original SW baulk of WSDB. However, Locus 43 was created to capture its full extent, requiring an extension of Locus 31 out to 5.73 m in length.