Looks like you gave Knopper galls on your acorns. A tiny wasp causes a chemically induced growth distortion of the acorn to house her eggs. These galls are found throughout Great Britain, and were initially thought to be a cause for concern. However it is now believed that they won't hurt the oak tree. Nothing needs to be done to control it. https://en.wikipedia.org/wiki/Andricus_quercuscalicis
This is a big old oak and around 90% of all the acorns are hosts to eggs. No other oak in the area has any sign of Knopper Galls.
Thanks for the knowledge.