At one point I thought they'd permanently put this off, but it looks like it's happening, although maybe it'll get cancelled again. Remember 'UK Stop Trump' (associated with Owen Jones somehow) was advertising for a paid staff member to organise the protest last year which just seemed ridiculous given Theresa May being here all the time.
If he'd visited shortly after the inauguration with mass protests in the US going on, I could see a major protest here, I wonder if they've left it long enough that it'll be smaller if/when it happens. With the TUC thread talking about the benefits and drawbacks of central London demos, realised this will probably be the next one:
https://www.independent.co.uk/news/uk/politics/donald-trump-uk-visit-dat...
The South Essex folks had this to say:
https://onuncertainground.wordpress.com/2018/04/28/just-imagine-what-cou...
tldr: They think its the perfect opportunity for mischief outside the centre of the capital!
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Personally I think If the Trump demo is a bigun, which is still possible, it could be a good chance to get radical literature into the hands of some folks who could be receptive, or create the opportunity for more radical actions.