Thanks @trickyearlobe - I now get a glimpse of the start screen. Still to short though. Applied @fba 's configuration, but it seems to make no difference:
Can't see what's wrong with it:
# head 200.conf
args: -boot menu=on,splash-time=20000 -vnc 0.0.0.0:15
boot: order=scsi0;ide2;net0
cores: 2...