In 2011 these galls were common on Quercus ilex, Holm Oak, at Mount Edgcumbe Country Park, Cremyll, Cornwall.
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Hi Plymouth Phil. Its interesting to see this gall, I've never actually come across it before. It fits the description in British Plant Galls Keys, Redfern, Shirley & Bloxham, 2nd edition. It is good practice that you had the identification of your unusual galls verified by an expert such as Graham Stone.