Analysis of information sources in references of the Wikipedia article "Stealing from the Saracens" in English language version.
How convincing is her argument? Much depends on how far you stretch the word Islamic. Notre-Dame's twin-towered front, Darke argues, is ultimately based on a fifth-century church in Syria called Qalb Lozeh (literally 'heart of the almond', meaning something like 'crème de la crème', Darke says). So we have a church – albeit a Middle Eastern one – influencing a later church. It's unclear to me where Islam fits in here.
And much of what Darke points to isn't (pace Wren) really "Saracen". Her story is most convincing in the discussions of arches and vaulting, which depend on engineering and whose development can be tracked, but she starts the book noting that Notre-Dame's double tower façade has a precedent in Syria's 5th-century Qalb Lozeh church—not just non-Islamic, but pre-Islamic. Similarly mosaics and colored glass pre-date Islam, and were widely used in classical Roman as well as Byzantine art and architecture. Spires and bell towers look like minarets, but there are examples (even in Europe) from earlier periods. Darke admits this upfront:
She freely admits in her conclusion that her comparison between a recently destroyed minaret in Aleppo and the Palace of Westminster's Elizabeth Tower - known as Big Ben - will probably raise eyebrows - and without evidence of any direct influence, the implication of one may well serve to distract from her argument a little, but nevertheless, this book is written with a great deal of enthusiasm and vigour.
Sometimes Darke overstates her case. Some of the connections she makes don't convince – a link she tries to make between Big Ben and the minaret of the Great Mosque in Aleppo is a bit of a stretch – but she assembles overwhelming evidence that extensive exchanges of ideas and knowledge took place.