The stabber was British-born of legal Rwandan immigrants, and from a devout Christian family. The incitement was the completely fabricated narrative that the stabber was an immigrant, which he isn't unless you count him being second generation, and/or a Muslim, which he isn't in any sense, hence the protests being mostly directed at immigrants and Muslims rather than anything actually relevant to the stabbings.

The relevant information is that they are neither muslim nor a migrant, two false claims that formed the basis for the riots.