‘Not worth the effort. I just know the lines and stations we need for our journeys.’ I love New York. The layout is so logical, at least uptown from 14th Street.

When Rosie had telephoned Isaac Esler’s wife she was very positive about some contact from Australia and news from the reunion. On the subway, Rosie said, ‘You’ll need an alias. In case Esler recognises your name from the Asperger’s survey.’

I had already considered this. ‘Austin,’ I said. ‘From Austin Powers. International Man of Mystery.’ Rosie thought this was hilarious. I had made a successful, deliberate joke that was not related to exhibiting some quirk in my personality. A memorable moment.

‘Profession?’ she asked.

‘Hardware-store owner.’ The idea appeared in my brain spontaneously.

‘Okaaaaaay,’ said Rosie. ‘Right.’

We took the E train to Lexington Avenue and 53rd Street and headed uptown.

‘Where’s the hotel?’ Rosie asked as I steered us towards Madison Avenue.

‘Lower East Side. But we have to shop first.’

‘Fuck, Don, it’s after 5.30. We’re due at the Eslers’ at 7.30. We don’t have time for shopping. I need time to change.’

I looked at Rosie. She was wearing jeans and shirt – conventional attire. I could not see the problem, but we had time. ‘I hadn’t planned to go to the hotel before dinner, but since we arrived early –’

‘Don, I’ve been flying for twenty-four hours. We are doing nothing more with your schedule until I’ve checked it for craziness.’

‘I’ve scheduled four minutes for the transaction,’ I said. We were already outside the Hermès store, which my research had identified as the world’s best scarf shop. I walked in and Rosie followed.

The shop was empty except for us. Perfect.

‘Don, you’re not exactly dressed for this.’

Dressed for shopping! I was dressed for travelling, eating, socialising, museum-visiting – and shopping: runners, cargo pants, t-shirt and the jumper knitted by my mother. This was not Le Gavroche. It seemed highly unlikely that they would refuse to participate in a commercial exchange on the basis of my costume. I was right.

Two women stood behind the counter, one (age approximately fifty-five, BMI approximately nineteen) wearing rings on all eight fingers, and the other (age approximately twenty, BMI approximately twenty-two) wearing huge purple glasses creating the impression of a human ant. They were very formally dressed. I initiated the transaction.

‘I require a high-quality scarf.’

Ring Woman smiled. ‘I can help you with that. It’s for the lady?’

‘No. For Claudia.’ I realised that this was not helpful but was not sure how to elaborate.

‘And Claudia is’ – she made circles with her hand – ‘what age?’

‘Forty-one years, three hundred and fifty-six days.’

‘Ah,’ said Ring Woman, ‘so we have a birthday coming up.’

‘Just Claudia.’ My birthday was thirty-two days away, so it surely did not qualify as ‘coming up’. ‘Claudia wears scarves, even in hot weather, to cover lines on her neck which she considers unattractive. So the scarf does not need to be functional, only decorative.’

Ring Woman produced a scarf. ‘What do you think of this?’

It was remarkably light – and would offer almost zero protection against wind and cold. But it was certainly decorative, as specified.

‘Excellent. How much?’ We were running to schedule.

‘This one is twelve hundred dollars.’

I opened my wallet and extracted my credit card.

‘Whoa whoa whoa,’ said Rosie. ‘I think we’d like to see what else you have before we rush into anything.’

I turned to Rosie. ‘Our four minutes is almost up.’

Ring Woman put three more scarves on the counter. Rosie looked at one. I copied her, looking at another. It seemed nice. They all seemed nice. I had no framework for discrimination.

It continued. Ring Woman kept throwing more scarves on the counter and Rosie and I looked at them. Ant Woman came to help. I finally identified one that I could comment intelligently on.

‘This scarf has a fault! It’s not symmetrical. Symmetry is a key component of human beauty.’

Rosie had a brilliant response. ‘Maybe the scarf’s lack of symmetry will highlight Claudia’s symmetry.’

Ant Woman produced a pink scarf with fluffy bits. Even I could see that Claudia would not approve and dropped it immediately on the reject pile.

‘What’s wrong with it?’ said Rosie.

‘I don’t know. It’s unsuitable.’

‘Come on,’ she said, ‘you can do better than that. Imagine who might wear it.’

‘Barbara Cartland,’ said Ring Woman.

I was not familiar with this name, but the answer suddenly came to me. ‘The Dean! At the ball.’

Rosie burst out laughing. ‘Corrrrr-ect.’ She pulled another scarf from the pile. ‘What about this one?’ It was virtually transparent.

‘Julie,’ I said automatically, then explained to Rosie and the two women about the Asperger’s counsellor and her revealing costume. Presumably she would not want a scarf to reduce its impact.

‘This one?’

It was a scarf that I had quite liked because of its bright colours, but Rosie had rejected as too ‘loud’.