"The punk-rock Joan of Arc of pop" ...That’s how Dave Stewart, formerly of The Eurythmics, summed up Lauren Mayberry after meeting her to work on ideas for Chvrches’ third album. And he may be on to something; ‘Love Is Dead’ filters religion, the refugee crisis and righteous politics through the band’s electropop-filter. The result? Grandstanding built for festival headline slots. Emily Mackay meets them in London.