The answer to that question is obvious; the exact extent can only be guessed at, though.
What we know from history is that these things spiral. We cannot forget it was when the Ulster Defence Association formed to protect the Protestant community that the Troubles took on its bloody and seemingly intractable nature.
That is what we are potentially dealing with, but only worse. There were no attacks in the Troubles purposefully targeting children, whereas this is a distinguishing feature in Islamic terrorism that transcends any local conditions (see Beslan in Russia, Manchester in England, Toulouse in France and Peshawar in Pakistan).
Indeed many attacks during the Troubles came with a warning so as to avoid casualties whereas this is lacking in Islamic terrorism. For instance, the 1996 Manchester Bombing destroyed much of the city centre but did not claim a single casualty as authorities were forewarned.
There are already “self-defence” forces on mainland Europe with an explicitly anti-Muslim bent, formed in response to Europe’s migrant crisis. Groups such Génération Identitaire represent a counterpart to the anti-state militia culture that exists more prominently in the United States, and which has been identified as terrorist threat by the FBI. These European groups are becoming normalised, as you can see in this video where prominent alt-right social media personality Laura Southern effectively gives Génération Identitaire free advertisement for their cause.
Luckily, Britain lacks the culture of para-militarism that exists elsewhere, but just as we must worry about lone wolf extremists so we must about lone wolf vigilantes. The stabbings in Portland this week exemplify how easy it is for a right wing fanatic to act out murderous intentions. And in the United Kingdom itself we have the example of the MP Jo Cox’s murder in the build up to the Brexit vote.
With this in mind it is paramount for all our sakes that we pare down any rhetoric and maintain perspective to guard against any reprisals.