According to my 'British and Commonwealth Warship Camouflage of WWII' book the refs are:
G5, Grey Black Soot
G10, Dark Grey, also known as battleship grey
G15, not listed
G20, Dark Green
B30, Dark Olive
G45, Green (light olive)
B55, mid grey
B15, Blue Black
I'd recommend this book, as it's got 7 pages of different Hunt class paint schemes from different times / theatres etc, here's a pic of just one of the pages