For the curious; the BBC has just put online a search engine (Beta version) giving free access to 16,000 records in WAV format.
The rights remain held by the BBC but the files may be used for personal, educational and research purposes, as stated in the license RemArc.
Go to: bbcsfx.acropolis.org.uk/
Good listening !
Source: France Inter : www.franceinter.fr/emissions/le-7h43/le-7h43-23-avril-2018