How ignorant can one be?
"In October 2020, Islamist terrorism remained the greatest threat to the UK by volume according to Ken McCallum, the Director General of MI5.[33] A report published in the same year found that of the 43,000 extremists on MI5's watchlist, around nine-tenths of the people on the list are Islamist extremists.[34] In July 2023, Suella Braverman, the Home Secretary of the United Kingdom, reiterated that Islamic terrorism was the primary domestic threat facing the UK.[35] Islamic terrorism represented 67% of attacks since 2018, 75% of MI5's caseload, and 64% of those in custody for terrorism-connected offences"
https://en.m.wikipedia.org/wiki/Terrorism_in_the_United_Kingdom