Well Al Quds day might be perceived as news worthy due to Hezbollah being officially considered a terrorist organisation by the United Kingdom along with the United States, the European Union, the Arab League, the Gulf Cooperation Council, Israel, Canada, the Netherlands, Australia to name a few.
Considering London has suffered from multiple ideologically possessed terror attacks it might be worth reconsidering how newsworthy open support of a terrorist organisation is.
Additionally, the Jewish community in London are particularly sensitive to the march as Al Quds day brings about hate speech towards them.
I'm not saying Al Quds day should be banned in London, but I think a public dialogue and debate should be had. In my estimation the lack of it is due to the 'multiculturalism is our strength' narrative bias held at the BBC.
Now I'm not saying 'multiculturalism is bad', I'm the product of it, and I definitely think it has benefits. But there are problems with it, which need to be confronted and worked through for a better society. Without a doubt these are sensitive, and ugly issues, but pretending they don't exist because you are captured by bias, will not solve the issues.
As for your Brexit comment, I believe you are suffering from recency bias.
In a report published in January 2018 called ‘Brussels Broadcasting Corporation?’, think-tank Civitas in conjunction with the group News-watch, monitored thousands of hours of radio and TV shows dating back to 1999 including the BBC flagship Radio 4 programme Today.
Of 4,275 guests on Today between 2005 and 2015 who talked about the EU, only 132 were Brexiteers.
Put another way, just 3.2% of Today interviewees were anti-EU, despite consistent public support for EU withdrawal throughout this time.
There are also a plethora of articles about this on Google, so in a way you are kind of proving my point because the data is out there but you didn't want to, or think to, look for it.
However I'm far less concerned about being 'right' and far more concerned about dealing with reality... and I believe the more people that deal with reality there are the better the world will be.