Muslim converts have an image problem. A handful, like Richard Dart, a Dorset native jailed last month, have been implicated in terrorism. Samantha Lewthwaite, who was married to Germaine Lindsay, one of the 7/7 bombers and himself a convert, is wanted by Kenyan police in connection with an alleged bomb plot.
Even without the taint of extremism, women are sometimes pitied for joining a religion accused of oppressing them. Despite these concerns, converts, for the most part peaceable, propel Islam's transition from an immigrant religion to a home-grown one.
Calculating convert numbers is tricky. The census in England and Wales only asks about people's current religion. Mosques do not record conversions centrally, and some new believers keep their conversions quiet. But using census data on race and religion, and questionnaires issued to mosques, Kevin Brice, a researcher at the University of Wales Trinity Saint David, reckons around 5,200 Britons turn to Islam every year, bringing the total number of converts to about 100,000.