Gall for ID, please

Gall for ID, please

Observation - Gall for ID, please - UK and Ireland. Description: An outside chance this, I think, but can anyone give an ID for this gall on Ash (Fraxinus excelsior)? I'm guessing that the causer is an insect so putting it in invertebrates but fungus is a possibility.

An outside chance this, I think, but can anyone give an ID for this gall on Ash (Fraxinus excelsior)? I'm guessing that the causer is an insect so putting it in invertebrates but fungus is a possibility.