She looked concerned. ‘What is it?’

He did not meet her gaze but looked away; the 23 bus, lumbering down the hill, passed within yards, and he saw for a moment his reflection in the windows, fluid, as on water.

‘What?’

She reached out to touch him. ‘Is something wrong?’

He shook his head. The social self reasserted itself: he was married again; there was nothing between him and Pat; they were in the street, in broad daylight, about to have what amounted to no more than a discussion between employer and part-time employee.

‘I’ve got a lot on my mind,’ he said. ‘Let’s get back to the gallery.’

They began to walk. ‘I’m sorry I’ve been out of touch,’ said Pat. ‘I’ve been working rather hard. And I’ve moved, you know. I’m in Warrender Park Terrace. A flat right up at the top.’

He could see it. ‘One of those big flats?’

‘Yes. I’ve got a round room, because it’s under the tower.’

He smiled at her. And then, unbidden, there came into his mind an image of Pat in her room looking out towards the crown spire of St Giles and to the Castle, like a ship, its ramparts protection against waves that were the clouds, and he saw her at her window and then as she walked, unclothed, across the room. It was a vision sent by Eros, who does not ask our permission for his whisperings.

He almost stumbled.

‘Careful,’ she said. And then, seeing his expression and noting the sudden high colour, she asked, ‘Are you sure you’re all right, Matthew?’

He sought to reassure her, but even as he did so, the vision returned and took his hand, and …

‘Oh,’ he muttered.

‘Matthew?’

He forced himself to think of something else, a trick mastered by every schoolboy troubled by wandering thoughts in mathematics lessons. In his case he had always thought of the Forth Bridge, and of its painting; a subject sufficiently devoid of emotional significance to distract one from the temptation of fantasy.

‘What are you thinking of?’ asked Pat.

The question, posed in innocence, could hardly be ignored. For a moment he was tempted to tell her, to say that he was picturing her in her flat in Warrender Park Terrace, but he could not do that, and so, without thinking, he answered, ‘The Forth Bridge.’

She frowned. ‘Odd. Why are you thinking of the Forth Bridge?’

‘I sometimes do,’ he said lamely. ‘The old bridge, that is. The railway bridge.’

‘Matthew, are you sure you’re all right?’

They were nearing the gallery, but she had stopped and laid a hand gently on his arm. She looked at him searchingly, and he realised then why he had always been so attracted to her: her eyes. And then he thought: how ridiculous that one can feel for a person on such slender, inconsequential grounds.