I notice this graffito while on the Victoria Line. I normally don't give graffiti more than a glance, but this is precisely because most graffiti is little more than 'artist'/gang signatures and random phrases. I've rarely seen racism etched or painted into the windows or walls of the tube, yet this is the third time I've seen this exact phrase three times on London underground trains and I've encountered anti-Arab racism twice in the past couple of years.
It's quite worrying to see such things on the public transport system, at least in the areas to which I travel. While antisemitism continues to worry British tabloids and broadsheets, not much seems to be being done about rising Islamophobia and anti-Arab racism in London and, perhaps, other areas of the UK.