I went grey the way most of us do - gradually, and then completely, somewhere between the lambing of 1998 and the market slump of 2004. I dyed it for a while, in the early years, sitting in the kitchen with a towel round my shoulders while the timer ticked. Then one April I was too busy with a difficult lambing to bother, and by June I'd stopped noticing, and by September I'd decided the woman in the mirror looked more like someone I'd trust.
It is strange and rather wonderful that the thing I gave up on is now the thing I am booked for. "Silver model" - it says so on my comp card, as if the hair were the qualification and the woman merely came attached. I don't mind. The hair earned it. Sixty-odd years of weather went into that colour; no salon in Cardiff could mix it.
What I notice, on shoots, is how often younger women on the crew come and ask about it. Quietly, at the tea table, the way you'd ask about something slightly forbidden. When did you stop? Weren't you afraid? What they're really asking, I think, is whether the world lets you. And I am living proof that it does - that you can let the colour come in like the tide and find, on the far side of it, more work, not less. Better light. Kinder lenses.
My advice, when they ask, is always the same: your hair is not going grey, it is going honest. The rest of you may as well follow it.