Whatever happened to Roman Catholics? They were not emancipated unti the end of the C18. Yet they were feared with a really good reason. Elizabeth I was condemned by the Pope as a heretic who shoud be overthrown, and, presumably put to death: an example of a Christian fatwa! The Pope blessed the Spanish Armada at the same time.
For long periods in our history Catholics were feared as people whose faith meant they , by nature, were enemies in our midst, whose leaders were set upon taking over the country and inflicting their faith on it. James II was deposed because of his Catholic tendencies. Much bloodshed and persecution was occasioned by these fears. We even had one particular terrorist conspiracy, the Gunpowder Plot, which would have made 9/11 look like a minor event.
Compared to all that, fear of Islam seems quite inconsequential, and pretty irrational in context.