Ex-head's terror arrest shock over protest cartoon
Jon Farley, 67, was held by police for nearly six hours on Saturday after being detained at a demonstration in Leeds. He was bailed and told on Monday he would face no further action.
...
West Yorkshire Police said it would consider any "learning" from the incident, which was first reported by The Guardian.
Mr Farley told the BBC officers "made a beeline" for him as the silent demonstration passed Kirkgate Market and handcuffed him before taking him to Elland Road Police Station.
Upon being told he was being arrested under the Terrorism Act because of the placard, he said he offered to show the police the original cartoon from a copy of Private Eye in his backpack, but that officers refused.
https://www.bbc.co.uk/news/articles/cz9kdq84j3lo

You can see that in no way "supports" the Palestine Action group; it just points out the British government's attitude and use of the law is crap.
Also:
a sign saying "Free Gaza" was held to be "supportive of Palestine Action". The woman threatened with arrest for that is now
taking Kent police to court.