What happened is best described in his own words.
The events were also described here.
Asa was awakened at 5:40 am by a police raid, said to be "on account of [his] social media posts", in connection with possible offences under sections 1 and 2 of the Terrorism Act (2006).
Asa has just published another article about it, here
Why the raid was scheduled for 5:40am was not apparent. Nor was why, to find material he has posted on the internet, looking on the internet isn't the way to go.
In any event, I encourage you to look at his writings that are so disliked by the authorities: his substack, Palestine is Still the Issue, and the Electronic Intifada give you plenty.
According to the World Socialist Web Site
Winstanley is associate editor at The Electronic Intifada, and has also written for Declassified UK, Middle East Monitor, Middle East Eye, The National, and Jacobin, and is the author of Weaponising Anti-Semitism: How the Israel Lobby Brought Down Jeremy Corbyn.
One must of course ask: does any of his writing amount to "encouragement of terrorism"? Probably. Does that bother me? Not a bit. Why? Because of the ludicrously broad definition of terrorism under the Terrorism Acts - under which I myself am a "terrorist" (on account of my service with the school cadets at my secondary school nearly 60 years ago). A future article will elaborate on this.
Of course, if anyone comes across anything he has written which offends against the Terrorism Acts and is actually objectionable, do let me know. For example, had he supported cutting off water and power from Gaza. (For this example of conduct offending against the Terrorism Acts I am indebted to Sir Keir Starmer.)
An internet search reveals that this event was hardly covered by the mainstream media, the one exception I found being the National (Scotland). So here are my reading recommendations from among sources that did cover it. (In some cases the articles on the web seem to be pay-walled but by subscribing I got them sent by email).
They understand that whoever controls the narrative controls the world.
So please don't make the mistake of thinking your attempts to disrupt their narrative control aren't working. Don't let anyone tell you your protests don't make a difference or your dissident speech poses no threat to the powerful. If what we're doing wasn't working, empire managers wouldn't be going nuts trying to stop us.
Panicked Zionist "elites" who run western states are lashing out in fear at their opponents. As their popular support evaporates in the face of clear evidence of appalling Israeli atrocities, they are resorting to the methods of fascism.
British counter-terrorism police visited the home of a man under suspicion of practising journalism. Disgustingly, the man had been raising awareness of Israel's genocide, and therefore had to be dealt with.
... Asa Winstanley. He is one of the most prominent figures in the worrying wave of radicals who believe genocide is wrong, even when Israel does it
Did I mention her work is described as "parody/satire"? Which is why I always enjoy reading her articles. Though last time I looked up to see what was the truth underlying one of her articles, I found the facts were just as extraordinary as the "parody/satire".
Personally, I don’t think any of the recent arrests/visits by counter-terrorism police are going to result in convictions. I hope I’m not tempting fate, but I think this is primarily about intimidation, and that is despicable in itself.
The mistake Asa made is the same mistake I made: he built up a platform and challenged powerful people. If you do that, those powerful people will come for you. All of us with a sizable platform are waiting to be next. It’s genuinely nuts.