I’m waiting for Lena, standing in the parking-lot, across from the entrance to the superstore. Surely she’ll be out soon.

A flashback to the early 90s. Waiting for Lena in another parking-lot, this time in a car outside a mall in Jeddah, Saudi Arabia. You could buy just about anything at the Jeddah International, and our kids — still small then — loved to watch the turtles swimming in the large rock-pool in the entrance hall. But that day they stayed with me in the car while Lena went looking for material for the children’s clothes she was making. Each dress or jacket had her special label: Amber.

While we were waiting, two Saudis positioned themselves a few yards in front of our car. In the cities, most Saudi men looked well-kempt and elegant in their traditional robes. But these two had unusually long, straggly beards and their white thobes were worn short, hitched well above the ankle. One was carrying a cane. Edwin noticed them.

— Who are those two men, Pop?

— They’re the mutawa.

— What are mutawa?

— They tell people how to behave.

— What, like you? Are you a mutawa?

I wasn’t, but I’d had a recent close encounter with Saudi’s religious enforcers. The mutawa were the unofficial police who at that time had the power to detain, question and punish anyone whose behaviour was, in their very strict interpretation of the rules, un-Islamic. There was a student in one of the adult language classes I was teaching, whose appearance was just like these two. He was a bit older than his classmates, keen, and always sat at the front, just to my right. One day he approached me after class.

— Can you help me, Mr Alan?

— Of course, Khalid. What can I do for you?

— Can you teach special English to my friends?

— What sort of special English?

— For when we meet women. Western women.

Now that was a surprise. Khalid and western women? It didn’t compute.

— Western women?

— Yes. We want to say them ‘Cover the head’. But nice.

Politely, I declined.

And now, 50 yards away, Lena emerged from the mall, her black abaya draped loosely over one shoulder, her hair glinting gold in the sun as she headed towards us. One of the men nudged the other, and they started moving in her direction.

Lena spotted them in an instant. Without breaking stride she took a sharp left turn and, with her free hand, started waving to an imaginary friend. The two mutaween changed course too. But now Lena had quickened, marching forward determinedly as if she’d suddenly discovered life’s purpose. They’d never catch her. They stopped, looked at each other, shrugged, and decided to head off into the mall instead. There’d be easier prey there.

Two minutes later, Lena came from the back of the car, wrenched open the door, and bundled herself into the passenger seat.

— Let’s go, driver!

So how would Lena fare in today’s test?

She was still in the store. Should I maybe go in and find her? No, I’d give her a bit longer.

It was the day after her Alzheimer’s diagnosis. I was still thinking about the consultant’s words: ‘a possible Alzheimer’s disease’, she’d said. So was there still an element of doubt? And what if she was wrong? That was why I was putting Lena through another test, a final confirmation. It was kind of like looking at my watch and realising I was late for an appointment, and then checking it again a couple of minutes later to make sure I hadn’t read it wrong or that time hadn’t miraculously started going backwards.

In the few months since our move to Salford, I’d noticed another personality change. In the old days, Lena was totally independent, a free spirit, always popping out to see someone or do something, whether it was just down the street or halfway around the world. But now she never went anywhere alone. To be fair, it was pretty difficult to do anything alone in our crowded house. One by one, our three kids had moved back to the new parental home, boyfriends and girlfriends in tow, drawn by the prospect of good company, good food, and free rent. So even when Lena went to the corner shop, it was either with me or one of the others.

But something had changed. Was it a sudden lack of confidence … or was this Alzheimer’s setting to work on her already? I was going to find out.

My plan was simple. Go to Tesco at lunchtime on Saturday when the place would be busy with everyone doing their weekly shop. Especially today, with Christmas only a fortnight away. I’d get the tomatoes I needed for dinner that evening, and then:

— Lena, I’ve just remembered, I need to go over to the Post Office with this letter …

I showed her the one I’d prepared.

— … and look, the queues are really long, so to save time, why don’t I go and do it now while you pay.

— OK.

— Have you got money?

I knew she didn’t. A few coins at the bottom of her handbag maybe, but these days she left money up to me. Cards were out of the question, now she couldn’t remember the PIN.

— Look. Here’s a tenner. That’s plenty, so why don’t you pick up something for dessert too – a cheesecake maybe?

— A cheesecake, and maybe strawberries too?

— Sounds good. You’ll have enough money for them too. And then, tell you what, let’s meet over at Costa and we’ll have a coffee. How does that sound?

A frown crossed her face.

— Costa, where we always go?

— Yes, just the other side of the car park.

We didn’t always go, but we’d been there enough times after shopping for Lena to know the place and where it was. I handed her the shopping basket, and she had the tenner in her other hand.

— So, what are you getting?

— These tomatoes. And strawberries.

— And a cheesecake, yes. And where are we meeting?

— Costa.

— You’ve got it. OK, see you in a minute. Have fun.

But I’m not in Costa. I’m in the parking-lot, watching for her to come through the door. Trying to be discreet, like a spy. If I’d had a hat, I’d have pulled the brim down over my eyes.

Finally, there she is. Without a shopping bag, I notice, but maybe she’s stuffed everything into her handbag. She pauses at the entrance, not seeing me. She looks right, looks left, and decides to walk in that direction, at pace. Then she stops, looks back, and turns to stride in the opposite direction. She pauses for a moment at the entrance, looks back inside, and then decides to carry on, away from the shops, away from Costa, and toward the main road.

— Lena!

But she doesn’t hear me. I start to run after her. Run? Stagger, more like it. I’ll need to get fit if I want to keep up with this woman.

— Lena! Wait!

This time she does hear me, thankfully. She turns, sees me, almost starts running herself, and when she reaches me she throws her arms around me.

— I couldn’t see you. Where were you?

— I’m here, Lena. I’m always here for you.

She releases me. So now I have to ask:

— Where were you going?

A pause.

— To Costa.