Charlotte looked across at her. ‘No? Some believe it’s the best painting in the world.’

‘Huh. I mean, I get that it’s a big deal but . . .’ Her eyes roamed the giant canvas. ‘Is that a dwarf?’

‘Yes, she was a maidservant.’

Lucy stared at it, looking more and more baffled. ‘There’s way too many people in it.’ She counted. ‘Jesus – eleven. Eleven figures. I mean, why? It’s hardly the Last Supper.’

‘No, but which figure is your eye drawn to?’

‘The little girl in the middle.’

‘Exactly. The Princess Margaret Theresa, she was the king’s only surviving child. The other girls are just her maidservants. See the king and queen in the mirror there?’ Charlotte pointed to the figures in the background. ‘Velásquez was the court painter, an incredibly ambitious man both professionally and socially. He had to reflect the importance of the Infanta, as well as pay deference to his sovereign. The little princess was actually betrothed to her uncle so these paintings were sent to him, as updates if you like, to show how she was growing up.’

Lucy pulled a face. ‘Eww, that’s so creepy!’

Charlotte laughed. ‘Yes, in this day and age it really doesn’t translate well, does it? But it was their equivalent of a photograph.’

They continued walking again, eyes alighting on the baroque frames of the vast murals, the rich colour palettes, stiff costumes and stylized scenes.

‘Nah, not sure this is my vibe either,’ Lucy sighed as they stopped below Bosch’s challenging triptych, Garden of Earthly Delights. ‘I like it all a bit . . . looser. Airier. More relaxed. Less hell and damnation and burning brimstones.’

‘Well, let’s keep walking. They have some stunning Fortunys through here. We could go see them if you like?’

‘Fortuny? Sure, why not,’ Lucy shrugged, her Valentino sneakers squeaking on the tiled floor. ‘How come you know so much about art anyway? Cambridge again?’

‘No, I read history there. I guess it was my parents I have to thank for this. They were always keen, forever dragging me and my sister round galleries as children.’

‘Including here? You seem to know this place well.’

‘Yes, here too. We visited every time we came to Madrid. My father always loved The Fable of Arachne. Do you know it?’

Lucy shook her head.

‘It’s not the most accomplished painting by any means but there are a few riddles in it that kept drawing him back.’

‘Huh. My mum only took us to the National Gallery once and that was because it was free and raining outside.’

Charlotte smiled. She was a big fan of these ‘walk and talk’ therapies; people opened up so much more when they weren’t subjected to direct eye contact, if the body could be distracted whilst the mind roamed . . . Sometimes, she thought the best thing she could do for her clients was take them on a road trip: London–Glasgow for the lesser afflicted; New York to San Francisco for the tougher cases. ‘You seem a lot brighter today. I was concerned about you when I left yesterday. Is this new optimism just down to remembering your love of art or has something else happened?’