Thanks Sam,
I assume my issue is not colourspace related but black level then? I have my LG TV set to use limited (16-255) and have a wonderful picture through my other devices (BD, Humax DVR, Chromecast and just normal TV). It’s as if after each reboot the Vero is using 0-255 for black level.
With my pi3 I used to use ‘hdmi_pixel_encoding=1 RGB limited (16-235)’ but can’t find a way to do that with the Vero - is it just a question of adding that line to a config file somewhere? config.txt doesn’t exist does it so how about advanced_settings?
I have found that, despite the dark startup picture, if I’m using a hardware decoder (which I’m not as you know at the moment 
) as soon as I play something the picture lightens and all is ok until a reboot. This does not seem to work under the software decoder though. So after each reboot, I have to re-enable the hardware decode, play something for a second to make the screen use the right ‘darkness setting’, then disable the hardware decoder again. Bit of a first world problem, but I’m looking forward to you fixing it Sam 
Thanks
-Mat