Thanks for that! Found more information on the Flyer website
here now that I know what I'm looking for!
UK Military METAR Colour Codes
Black - Airfield closed for non-Met reasons.
Red - Cloud under 200ft, and/or Visibility under 800m.
Amber - Better than Red, but cloud under 300ft, and/or Visibility under 1600m.
Yellow - Better than Amber, but cloud under 700ft, and/or Visibility under 3700m.
Green - Better than Yellow, but cloud under 1500ft, and/or Visibility under 5km
White - Better than Green, but Cloud under 2500ft, and/or Visibility under 8km
Blue - Cloud 2500ft or above and Visibility 8km or more
'Cloud' in this case is the lowest cloudbase designated as SCATTERED or worse.
RC