Tomsdad, The phrase from the extra letters could not be a cryptic clue to BMSR since the first word is singular, not plural. The first three words of the phrase indicate a letter; the fourth word indicates a short word; the last two words indicate an abbreviation. Put all that together and you get the thematic name.
Considering the lightweight, and possibly obscure, nature of the theme the preamble should most definitely have said that the extra letters provide a cryptic clue to the identity of the person. Not to do so means solvers just waste time looking for sources of a possible quotation.