Euura bridgmanii

Formerly known as Pontania bridgmanii.

Galls of this species are similar to those of Euura proxima (and presumably Euura triandra but I've not seen those) but can be told apart by identifying the specices of willow. These were on sallow, almost certainly Goat Willow (but possibly hybrid: sallows resembling Goat and Grey Willows grow alongisde eachother here and have not completely eliminated the possibility that some are hybrids).

Euura bridgmanii galls on Goat Willow, North Elmham Cathedral Meadows (Norfolk, UK), 18th September 2020