Taking another closer look at the initial photo, and importing it to photo software, eyedropper tool shows the two areas almost similar in grey tone:
Yellow was suggested for tactical marking colour, but then it doesn't match the maple leaf - unless the leaf was not painted yet and left white, or is (metallic) gold and giving off a sheen to make it appear light?
It does seem a lighter than usual blue was used on both the AoS and tac mark. The example I've made is suppose to be cobalt blue, though it's not on the 1944 British Standards Chart:
regards,
Jack