For that usage I need an omnidirectional rather than a shotgun microphone. I also need it to have shielding to prevent all that nasty handling noise. I don't have a background in audio technology, so need to rely on reviews to guide my choice of equipment. This was fairly easy with the field recorders - which are extensively reviewed on the Internet. But with microphones I had a harder time. It seems that very few people choose to review microphones. Perhaps I shouldn't have been surprised to discover that.
I eventually decided on the AKG D230. I managed to buy a second hand one on Ebay - which should arrive sometime in the next couple of weeks. When it does I will offer my own very inexpert review.
As for the question of what audio interviews am I intending to conduct - it is connected to my interest in dyslexia. I'll say more about that in a future blog post.