I’d say that she has looked after her skin from a very early age, stayed out of the sun and spent a lot of money on the absolute best facial aestheticians she can find. Fair play to her, she looks fantastic.
I also think she dresses very carefully. I bought a dress like hers from St Bustier once (the Nigella dress!). The thing had the sort of terrifying elastic tension that could hold up a bridge but, once i’d wriggled into it, I was stunned at how absolutely fucking amazing i looked! The effect was astonishing but my God it took some wearing. The pressure! You definitely can’t go for a pee in a hurry.