But I'd assumed that pretty much anyone with a knowledge of British history (note - that doesn't mean a GCSE at O or A level, alas) would have heard of the Barbary Coast Pirates, Muslim sea-rovers who operated off the coats of Britain in much the same way that the Vikings had 800 years previously.
Seems to have come as quite a shock to the Divine Ms M.
The Dumb One calls it Four Hundred Years Of Dhimmitude, but it ain't really. It's just what they did. It was the culture, man. And the Knights Hospitaller of St John (yes, the forebears of those nice First Aid people) and other Christian corsairs took their share of slaves when intercepting the ships of the Ottoman Empire.
Perhaps it might stop liberals beating themselves up about slavery to be reminded that it had been an integral part of most Islamic economies for seven hundred years before John Hawkins started sailing West African waters, continued into modern times in Arabia, and continues today in places like Sudan.