'London stabbings' is the new Russia Today/alt right/Bannon dogwhistle.
A bit like 'Soros ... elites ... conspiracy'.
Apparently, stabbings are the result of having a Muslim mayor and EU immigration.
Not austerity and under-funding of intervention programmes/community policing.
It's all over the place on the internet.
It pops up in comments sections and twitter replies in the most random way - often with quite strange spelling. And posted by someone with a v odd avatar and numbers after their posting name.
My advice: any post you see wimbling in about this particular trope, imagine the troll farm in Russia in which it originated, or the weird MAGA types, frothing around in a masturbatory frenzy as they dream up ways to get everyone as riled up and bonkers as they are.
Then ignore.