Bird Cherry-Oat Aphid Rhopalosiphum padi

This rolled-up Bird Cherry leaf contained a colony of aphids. There were no alates present. A larger, darker aphid was visible when I uncurled the leaf (top left in second photo) and when I examined them the next day there was a green aphid among them (final photo) which I assume is a mature specimen of the same species. The pinkish-red suffusion around the base of the siphunculi on this individual was also shared by the darker one as well as some of the (older?) grey ones.

Bird Cherry-Oat Aphids Rhopalosiphum padi, Wendling Beck Environment Project (Norfolk, UK), 29th April 2023