chmod 600 made no difference on the existing file.
Yes, the file was (incorrectly) created in windows (as a .txt file & renamed) and written to the Vero4K using the SMB client add-on. (i.e. this was a Windows (CR LF) UTF-8 text file.)
Recreating it using the native nano editor solved the problem (i.e. this is now a UNIX(LF) UTF-8 text file)
Multiple newlines (LFs) after the password, when created using nano, had no effect and .smbcredentials was still usable.
Spaces in the username of the .smbcredentials file also don’t work. They cannot be forced by preceeding the space with the ‘\’ character (however this is possible when using them in the mount specification to autofs. )
fzinken - thanks for your help and patience, I’d recommend updating your ‘how to guide’ for autofs with these points.
Chris.