Willow Gall Sawfly (Pontania (Potania) proxima)

Willow Gall Sawfly (Pontania (Potania) proxima)

Observation - Willow Gall Sawfly (Pontania (Potania) proxima). Description: A gall - presumably formed by an insect - on a weeping willow (Salix sp.) Can anyone offer an ID, please? Edit: Changed to match Simon's ID. Many thanks.

A gall - presumably formed by an insect - on a weeping willow (Salix sp.) Can anyone offer an ID, please?
Edit: Changed to match Simon's ID. Many thanks.