Did anyone get a definitive answer of where the possible shaft/sap was?
Reading the descriptions, it appears, to me, to be the "S Works" in, what is now the Garenne de Treize. ("Peronne Road" in the description may be a little misleading, BTW, as ,along the road to Peronne (!) there was a trench named "Peronne Road" which split into "peronne Rd North Ave" and "Peronne Road South Ave" so I believe that the events must have taken place south of this trench before the split (but still SE of Maricourt) - this can only lead directly to...."S Works" and it's associated saps.)
Dave