Maybe WBMP means Wim's Bubble Makes Puffy
If slow music, played in single beat, is already so slow that it is a very acceptable, if not the only, way to make it sound musically, isn't it absurd when played in double beat? That applies to both pieces that I play here. They are the numbers 9 and 10 from "Meditaciones religiosas" opus 122 by Louis Lefébure-Wély, a Funeral March and a Prayer, both preceded by an Introduction. Both the metronome numbers and the playing times of these two pieces are given by the composer. This applies to the entire collection of 10 pieces. These two pieces sound beautiful in single beat, precisely because of their slow tempo. In double beat they would lose all of their musicality and sound banal. Therefore I didn't even play it in double beat. For me that is an obvious reason that Lefébure was a composer who started from single beat. This also applies to his other compositions, including his piano etudes, which have the same difficulty as those of, for example, Clementi, Bertini, Cramer, Heller and Moscheles. Shouldn't the etudes of these composers also be played in single beat? And isn't that also the case for a lot of other music with metronome markings? Or would it perhaps apply to all 19th century music? If so, then the double beat theory was invented by people who hate fast music, or can't play it themselves. They call their slow tempo quasi scientific WBMP. I think that all musicians from the 19th century, and the first half of the 20th century, have never heard of WBMP, and therefore never applied it as such, because it didn't exist.