Small galls on young oak leaves
No interactions present.
These are the sexual generation galls of Neuroterus quercusbaccarum, the asexual generation of which causes spangle galls later in the year. They are often referred to as 'currant galls' rather than the C. quercusfolii 'cherry galls' which are generally larger and appear later in the summer. Currant galls also appear on male catkins.
Thanks Peter, that's really helpful. I have revised the id based upon your comments.
Lat/Lng: 52.7025, -1.2071
OS grid ref: SK536119