No british person writes F like that and if you are graffiti and it is hate words then there is no way you are taking time to write it so neatly like it was.
Graffiti artists are all about commuting their feelings and believes. It can be cryptic to communicate with one another or more clear for the wider public to see and understand their message. So absolutely they would take the time to write something out neatly in graffiti style.
And yes, the average Brit who struggles with joined-up writing would never even attempt drawing the letter F with flourishes. However, graffiti taggers would incorporate this for personal taste and uniqueness. And it is very likely that they would take the time to study or take inspiration from calligraphy available online or at hand.
Just compare the anti-Polish graffiti smeared at POSK with the other following examples of British calligraphy particularly the letter F:
there's a youth organisation called OMP that meets in the same building.
Yesterday you said OMP was a conservative think tank in Krakow which most people never heard of.
Today it is a youth group inside the same premises as POSK! And the POSK chairwoman has been giving interviews and never even put two and two together. Not even the British police, politicians and media could figure out your latest bit of evidence. Have you contacted any of the aforementioned with your tip or are you going to keep guessing?
Here is a list of youth groups in Hammersmith:
Nothing even close to the initials OMP.