The Dean hangs her peacoat on a peg, then covers it with his own tweed jacket. As she watches she catches herself wondering what it would feel like to fold her own self into him, to be enveloped in his arms. Where did such dizzy notions come from? Shocked at herself and perturbed at the thump of her heart, she drops her gaze and breathes herself back to calmness while Luigi shows them to a tan leatherette banquette set into the right-hand wall at the back of the restaurant. The Dean waits for her to sit and the waiter waits for both of them, before placing the menus on the table and announcing a couple of specials. The Dean thanks him and watches him leave before turning to Nevis and in a rueful tone says, ‘I wish we were having lunch in happier circumstances. The food is really wonderful.’

She nods, anxious that the phrase ‘happier circumstances’ is an indication that the conversation is about to head into choppy waters.

The Dean says, ‘You’ll have a glass of wine, won’t you? We could probably both use one.’

With a wave of the hand he signals the waiter over and orders two large glasses of Chianti. They wait in silence until the wine arrives. She is aware that he is looking at her but manages to avoid his gaze, afraid of embarrassing herself by her girlishness. Is it possible he finds her attractive? No, she can hardly dare to imagine that’s it. Admires her perhaps, is impressed by the byways of her mind.

‘You seem a little unsettled,’ he says, smiling kindly. ‘Hardly surprising in the circumstances. We’ve had news from Satnam’s parents this morning. She’s stable, so that’s a good thing.’

‘Yes,’ she says, touched by his concern but torn, too, by his assumption that Satnam is the cause of her anxiety because the fact of the matter is that in the last ten minutes she has almost – but not quite – forgotten her friend.

When the wine appears, he raises his glass. She reciprocates, and gulping down half the contents, allows herself a moment of fantasy. Here they are, a couple of mathematicians joined together by their appreciation of the perfection of algebra and geometry.

He opens his mouth to speak and she braces herself, hoping that whatever is coming next, she will be able to meet it. The Collatz Conjecture or perhaps – she blushes at the thought – the Kissing Number Problem.

Instead, he says, ‘I expect you’ve heard about Jessica Easton? Nothing stays off social media for long.’

She catches his eye briefly then tilts her head away so that he will not see her anguish as the world comes crashing back in. Is this why the Dean invited her to lunch? To talk about a dead girl?

‘Yes, I heard.’