Like this individual:
Who were the ones in this thread who out of the blue and without any evidence whatsoever began blaming Poles for the vandalism done at POSK?
Oh, that's right, it was these British nationals who are deflecting blame away from their nationalist brothers and sisters back home:
The handwriting looks more Polish than British. Far more.
I reckon that graffiti was done by a Polish person hoping to make some trouble.
And your absurd explanation for the graffiti:
Polish internal politics.
OK Sherlock, here is a link to London-based POSK's website regarding their history and mission:
Here in particular is a copy of POSK's Articles of Association when they were incorporated:
And here is a link to the website for Krakow-based Ośrodek Myśli Politycznej (OMP):
Notice that all links provided are in English for your benefit.
Now, armed with this information, by all means dazzle everyone with your instinctive and effortless crime solving skills and instantly crack this case wide open for everyone and long before the Metropolitan Police ever would.
Go on, everyone on the forum is waiting.