Nationalist terrorist organisations already exist.

Arrests for associating with these groups have been made recently.

Fascism is now playing respectability politics with a "suits not boots" strategy. We are seeing this in Europe too.

If things don't improve groups like Britain First or UKIP will grow in support.

Terrorist could have a few definitions. A group being proscribed by the UK government seems straightforward. One of their members being jailed for terrorist offences sends indicative but not necessarily a slam-dunk: if a member of Greenpeace committed a terrorist act, that doesn’t automatically make Greenpeace a terrorist organisation.

“Massive” absolutely needs a number put on it. The British National Party got 1.9% of the vote in 2010. Was that massive? For an openly fascist party, yes, for a political party seeking public support of their goals they didn’t get close to signing a single seat. If a British IRA existed, and had some support, you’d expect to see polling on it, so maybe put “x% support / strongly support $ORG in a YouGov poll” or something similar.

@Noit can we assume there would be good quality polling?

@benjaminIkuta as a point of comparison, More in Common has run limited polling on Tommy Robinson. IMO It’s hard to imagine any organisation with “massive public support” being run by someone less well-known than Tommy Robinson unless it was deliberately run in a decentralised manner. I wouldn’t assume there would definitely be polling, but if you had “polls >x% in a BPC-approved pollster poll” as one of several resolution criteria then that could be a fairly strong signal.

Should we spend a lot of time litigating the difference between terrorism and non-terroristic insurgencies?

@asmith how about "Armed organization which describes itself as "British nationalist" "British patriot" or some variant thereof or describes itself as opposing mass immigration claims responsibility for violent killing of 10 people or more within a one year period before August 10th 2030"?