The photo shows him with his first coats of gesso on. I use Anthony Dew's recipe, except I find I have to add a lot more whiting than he says, else it's way too watery. I don't put on a coat of size first either, as it seems to make the horse wet to no purpose.
It looks good in the picture, but in the daylight on the balcony I saw loads of little dents and gaps that I will have to fill with gesso. Surprising, as I thought I'd done a thorough job of filling and sanding.
The gesso is over the edge of his eyes (now fixed in with filler) and I will clean it off when the gesso layer is complete.