She was particularly touched that Charles wanted the prenup to say if they split up, she should have the house. Overall in the US around one in five married couples has a prenup. In the UK research suggests around one in ten couples now has a prenup, following a legal shift in England towards greater recognition. Here too it is younger couples leading the way, with around one in three married under-35-year-olds having signed one, according to surveys. "I was very open to the idea [of a prenup]," says 33-year-old Becca, especially after her first marriage "didn't end very well".