Yes, John Cleese was a Lib Dem a few decades ago, but the kindest thing you could say about his politics today is that they're those of increasingly grumpy old man.
And Claire Fox and Brendan O'Neill have roots in the Revolutionary Communist Party, so their far-right lunacy might actually be part of some deep-cover accelerationist strategy. But that's not actually any better, is it?
Is it the same for the signatories from other countries? Are there actually any significant left-wing or centrist figures?
Or is this just disingenuous cant?
Left-leaning: Žižek, Stone, Varoufakis, Hedges, Sachs, Liu;
Centrists: Assange, Snowden, Robbins, Fang, Maté.
The majority would likely be to the right of the centre, closer or further away.
I suppose that some degree of interpretation will come into it in absence of a clear definition and self-expression of political adherence. Some of those could be catalogued as nothing more than Hollywood progressive liberalist, some radical civil-libertarians etc.