This reminds me a touch of MacColl's Critics Group insistence that singers should restrict their repertoires to their authentic geographies of origin - whilst himself being a Salfordian wrapped in ancestral Scottish heritage, singing songs from right across the realm, and a prolific writer of new material to boot.

As in so many fields, the high priests are above the covenants required of the flock...!

There's much truth in this, but I also suspect that there was plenty of creative thinking going on in order to justify given song selections, in the same way that singers in 'theme nights' will dream up ingenious arguments to excuse a song of dubious relevance to the theme. MacColl could at least claim authenticity in respect of his Scots and Lancashire songs, and also anything he'd written himself that emanated from his own cultural experience. Lloyd could arguably have done the same for his maritime songs, although there is a very interesting comment in Peggy Seeger's memoir to the effect that Bert was most adept at constructing convincing fake traditional songs at the drop of a hat, to subvert the dictates of the Policy.