Mrs Adrian van Montagu, née Anne Mabel Olivia Trouton Possibly 1910

This is a portrait of Mrs Adrian van Montagu, painted by Philip Alexius de László; he's really got into the nitty-gritty of colour here, working it right into the surface in a way that feels so free. Look closely, and you'll notice how the brushstrokes build up, almost like layers of thought. The paint's applied in a way that celebrates its own materiality, thick in some parts, thin and transparent in others. It gives her dress this kind of luminous quality. My eye keeps going back to the details in her face and the way he has rendered the planes of her bone structure. The colour isn't blended perfectly, you can see all these little strokes next to each other, so everything shimmers. De László reminds me of Sargent in his approach to portraiture. And like a lot of painting, it's about the process, about thinking through the medium, about letting the paint speak, which is really what makes it interesting.