Accused of ‘playing God’, a trio of British medics persevered – and changed the lives of millions worldwide. The makers and stars of Joy explain why there were ‘many tears’ during filming

‘It’s just so weird, having children,” says Bill Nighy. “The whole thing is like science-fiction. Human beings make decisions and have ideas and choose their partner and it’s all so reckless and marvellous. It’s such an extraordinary thing to attempt. Maybe it’s just my age, but I just think of all the energy involved to have and raise children, you know?”

I hear him gliding down the street, phone in hand, offering some sort of gorgeous apology to a cafe door. “And then there’s this human being who turns out to be somebody quite independently of whoever might have been involved in their creation. They’re this completely other thing. And they’re also, in the case of my grandchildren, edible.”

Nighy is a highly covetable grandfather. His date to the Oscars two years ago was a stained Sylvanian bunny (“My granddaughter’s schedule intensified,” he explained, “and I was charged with rabbit-sitting responsibilities”). This year he has leant his voice to no fewer than five children’s animations. And now he’s playing the real-life gynaecologist who pioneered IVF.