Not just that: https://www.bbc.co.uk/news/articles/ce950111xk7o

"Corner, a former student at the University of Oxford, was also convicted of causing grievous bodily harm after he fractured Sgt Kate Evans' spine with a sledgehammer in the raid."

But again, let's be clear: that justifies the conviction of the person with the hammer. Not the people with signs.

Ugh, thank you - I was not aware of this. I agree with you - this should have got that person prosecuted. People with signs is perhaps a tad exaggerated.