Nut Scale Eulecanium tiliae
These were on twigs of a Lime tree in a park. I'm not certain of the ID, however visually it is a good match and this is the only such species that I have managed to find that is known to occur on lime trees. I welcome either confirmation or advice of any other possibilities to consider.
presumed Eulecanium tiliae, Wendling Beck Environment Project (Norfolk, UK), 27th May 2025