I think I may now have found the answer. In a rather wonderful essay entitled 50 Years of Stupid Grammar Advice, Geoffrey Pullum (head of linguistics and English language at the University of Edinburgh and co-author of The Cambridge Grammar of the English Language) puts the blame firmly on two gentleman named William Strunk and E. B. White. These learned coves may not be terribly celebrated on the European side of the Atlantic, but in America they are regarded by many as the ultimate authorities on good writing. They produced a book called The Elements of Style which is stuffed full of ‘rules’ on what good writers should and should not do – and one of the greatest writing sins, according to Strunk and White, is the use of the passive.
Pullum has no time for that. He does not pull his punches. In his opinion, “both authors were grammatical incompetents” and, to prove his point, he goes on to rip their anti-passive advice to linguistic shreds...
“What concerns me is that the bias against the passive is being retailed by a pair of authors so grammatically clueless that they don't know what is a passive construction and what isn't. Of the four pairs of examples offered to show readers what to avoid and how to correct it, a staggering three out of the four are mistaken diagnoses. "At dawn the crowing of a rooster could be heard" is correctly identified as a passive clause, but the other three are all errors...”
Suffice to say, Professor Pullum’s attack on Strunk and White is music to Sir Courtly’s ears. I heartily recommend it.