‘What are those idiots doing?’ asked Peter Maxwell morosely. He was obviously unaccustomed to being kept waiting.

‘Colin is trying to teach them to cast,’ I said. Peter Maxwell shook his head in disbelief and walked across the room to a large round table and began flicking through the pages of Country Life, looking at the advertisements.

‘Where do you think the sheikh is?’ asked Maxwell, pushing the magazine away from him abruptly. ‘How long will we be kept waiting like this?’

‘I am sure he will be along shortly,’ I said. ‘He has probably landed at Inverness by now.’

‘Doesn’t he know who I am?’ Peter Maxwell asked me. ‘Haven’t you made it clear-’ There was a soft sound, the swishing of robes.

‘Gentlemen, Mr Maxwell, I am sorry to have kept you. Welcome to my home.’

The sheikh was standing in the doorway. I introduced Peter Maxwell even though the sheikh quite clearly knew who he was, and then stood apart, feeling detached and miserable, while they talked.

It was raining in my heart. The trite words of the song rattled around my head and would not leave me. I felt hollow inside, all that time after Mary left for Geneva. And while I should have been thinking about the problems of the Yemen salmon project, problems so vast and complex they should have engaged every moment of my time, every last calorie and atom of energy, I was thinking about Mary.

When Mary left for Switzerland, there was a vacuum in my life.

I had always thought of myself as a sensible, stable person. When we did our annual performance appraisal forms at work, we had to write about our colleagues. I know that when my colleagues wrote about me, the first word they put down was always ‘steady’. The next was ‘sensible’. Sometimes I was described as ‘committed’. Those words were a true picture of Dr Alfred Jones, as I once was.

I still remember the first time I met Mary. It has been in my mind often, since she went away. We were both at Oxford at the same time, towards the end of the 1970s. We met at an Oxford University Christian Society evening in our first term. It was a wine and nibbles evening, a very good way of socialising for those of us who felt we could not spare the time to go to parties every night.

I remember that I first caught sight of Mary as she stood by the door with a glass of white wine in her hand, casting an appraising glance around the room. She looked-but I can’t remember how she looked. Sharp-featured, slim, intense, I suppose-much as she is now. She has not changed much over the years, physically or in any other way.

She saw me clutching a glass of soda water and she smiled and said, ‘Don’t you trust the wine?’

‘I have an essay to finish tonight,’ I replied. She looked at me with approval.

‘What are you reading?’ she asked.

‘Marine biology. I am specialising in fisheries science. And you?’

‘I’m an economist,’ she said. She did not say, ‘I am reading economics,’ or, ‘One day, I want to be an economist.’ In her mind she had already become what she wanted to be. I was impressed.

‘Is this your first term?’ I asked.

‘Yes.’

‘Are you enjoying it?’

Mary sipped her wine and looked at me over the rim of the glass. I remember that look, level, challenging.

She replied, ‘I don’t think enjoyment is relevant. If you asked me, am I managing it, I would reply that on an allowance of forty pounds a month I am finding it difficult but not impossible. My view is that if I cannot successfully budget even on such a small sum of money as that, then really I should not be studying economics. After all, economy starts at home. And you, are you enjoying what you do? I know little about zoology. I imagine it is a very relevant and valuable subject. Do you know, in my year at college nearly every other girl is reading English literature or history. What can be the point of that?’

And so we were off. We went out to supper together that night, somewhere very economical, and Mary talked about her wish to do a thesis on the Gold Standard and I went on, I fear at great length, about the possibility that one day England ’s great industrial rivers would become clean again, and the salmon runs would return.

By the end of the summer term we were going out together regularly, and so it was not a major surprise when Mary suggested I take her to a May ball. It was perhaps a little unusual for Mary to depart from her normal frugality, and spend money on a new ball gown (even if it was from the second-hand shop) and having her hair done. But then, as with everything in Mary’s life, it was all part of the plan.

We went with a group of friends and dined and danced together. We spent most of the evening in the marquee set up in the college quadrangle. The DJ played a song that night over and over again-‘I’m Not in Love’ by 10CC.

At some point early in the morning I found that Mary and I were somehow sitting alone at a table apart from all the friends we had come with. Mary was looking at me with more intensity than usual. We had both drunk a great deal more wine than we were accustomed to and had stayed up much later than was usual for either of us. I felt that light, feverish feeling that can overtake one in such circumstances. A sense of unreality combines with the feeling that anything might be possible, sometimes with unlooked-for results. Mary reached across the table and took my hand. It wasn’t the first time she had done so, and we had even kissed once or twice, but unnecessary emotional display was not something she approved of on the whole.

‘Fred,’ she said. ‘We get on well together, don’t we?’

For some reason this remark made me swallow. I remember my throat going dry. ‘Yes, pretty well, I think,’ I said.

‘We have so much in common. We both believe in hard work. We both believe in the power of reason. We are both achievers in our different ways. You are more academic; I am more ambitious in a worldly way. I want to go into the City, and you want to become a professional scientist. We both want many of the same things from life. Together we make a great team. Don’t you think that’s true?’

I began to see where this might be going, the feeling of unreality I had sensed earlier grew stronger, and I spoke and felt and thought as if I were in a dream.

‘Yes, I suppose it is, Mary.’

She squeezed my hand.

‘I could imagine spending my life with you.’

I didn’t know what to say, but she said it for me. ‘If you asked me to marry you…’

The DJ was playing ‘I’m Not in Love’ again, and I wondered what those words meant. The truth is, I didn’t know about love just as I didn’t know about fear of death or space travel. It was something I hadn’t encountered or, having encountered it, had not known it for what it was. Did that mean I wasn’t in love, or did it mean I was in love, but didn’t know? I remember feeling as if I stood at the edge of a great cliff, tottering towards the precipice.

I knew I had to say something, and then I felt Mary’s foot press against mine, hinting of other possibilities, so I said, ‘Mary, will you marry me?’

She flung her arms around me and said, ‘Yes, what a good idea!’

There was a burst of cheering from some of our friends at the nearby tables, who had either worked out, or had been forewarned of, what had just happened.

Of course ours was a sensible engagement. We agreed that we could not get married until we had both graduated and were in employment and our combined salaries had reached more than £4000 a year. Mary had calculated (as it turned out, accurately) that this would be enough to pay the rent on a small flat somewhere on the outskirts of London, plus an allowance for travel, a week’s holiday a year, and so on. Long before Microsoft Excel Mary had intuitive software in her brain that allowed her to see the world in numbers. She was my guardian and my guide.