C ynthia Erivo is contemplating her favourite crisps, the ridged American brand Ruffles, as we sit talking in a quiet corner of a west London restaurant. Dressed all in black and sporting her signature elongated nails, she is known for her healthy lifestyle, but everyone, it seems, has their vices. “Ruffles are just perfect,” she says. “When you get a good batch, and the salt-to-potato ratio is perfect … it’s amazing.”

Erivo has just touched down after singing in Phoenix, Arizona, the night before, and has been running me through the health routine that helps her maintain her frantic schedule. Before her concert, there was the Dior front row at Paris fashion week, and she has just been announced as a guest host on SNL UK. Erivo doesn’t drink alcohol (today she orders some peppermint tea); she’s vegan; she doesn’t eat airline food, only her own prepacked meals. She even has an infra-red sauna “to help me heal from the inside”.…