It's interesting that - for all the attempts on this forum and elsewhere to spin the balloon campaign as free speech advocacy and legitimate political opposition to Khan's mayorship - according to your photo it seems to be heavily associated with Trumpies presumably butthurt that somebody poked fun at their idol.
An
opinion piece on Metro.co.uk written by a representative of the fun pokers would appear to bear this impression out and even links the campaign funding with some of those far right extremists we're not supposed to be mentioning right now.
I wonder if that's what scared any neutral supporters away and thinned the crowd to single figures. Kinda doubt it , though.