Thank you. I've now read [[[This thread.](Raspberry pi 4 access point].
Alas, no better outcome. I think this is the crux of it?
Sat May 30 22:56:52 2020 daemon.notice netifd: radio0 (621): Command failed: Request timed out
Sat May 30 22:56:52 2020 daemon.notice netifd: radio0 (621): Command failed: Not found
Sat May 30 22:56:52 2020 daemon.notice netifd: radio0 (621): WARNING (wireless_add_process): executable path /usr/sbin/wpad does not match process path (/proc/exe)
Sat May 30 22:56:52 2020 daemon.notice netifd: radio0 (621): Command failed: Invalid argument