Does rosemary oil really make hair grow? And can you reverse greys? A trichologist debunks your hair myths

I have my hair icons; don’t we all. Brigitte Bardot is up there, forever making me yearn for an abundance of hair, tousled just so. Then there’s a Bond-era Sophie Marceau, hair streaming down her back, long fringe framing her face. More recently Daisy Edgar-Jones’ ‘do has made me a bit weak at the knees, the caramel lengths making her fawn eyes look even more huge.