Thanks Philippe - and thanks for taking the time on a lovely Sunday afternoon to look at this. Your support is second to none. The files have been created on various android phones and I’m not sure what sort of library might have been used to create them. I used VLC to convert them and presumably VLC is using FFmpeg, but that is a guess. I’m going to try MrSoundman’s suggestion.
If if is any comfort SoundForge couldn’t read it or Samplitude though for some reason Samplitude wanted me to activate AAC - which I did but it still couldn’t read it. Digital Performer couldn’t read it, I didn’t even try Sadie! dBPpoweramp couldn’t read it either.
Ta like, ppm6.