Small oval unstalked galls in oak buds, with a purplish velvety pubescence.  The bud scales can be seen at the base of the gall.  All records from VC55 have been on the epicormic buds on oak-tree trunks.

The agamic forms are the familiar Cherry Galls.

Cynips longiventris sexual galls are of similar size but with greyish pubescence, short stalks and no bud scales 

Close-up photos of galls showing bud scales 

Oak trees

Spring

The agamic gall is very common, but the sexual galls are rarely recorded

See British Plant Galls, 3rd edition (Redfern & Shirley, 2023)  and  species page on Plant Parasites of Europe (Bladmineerders)