I don't suppose you remember me. Why should you? It was a long time ago and for you, it must have been just a chance encounter. For me it was a life-saver. Literally. Like the time I got out of my depth beyond the breakers at Woolacombe and shouted "Help!" and a young surfer pushed his board out to me and towed me to a place where I could stand again.

But this time I didn't shout. I couldn't.

My mother was dying in hospital. She'd had a massive stroke which had robbed her of speech and movement, and no one could tell us how long she would stay like that. So Dad and I established a routine. Dad went to the hospital in the morning and I'd do the afternoon visit. In the evening we went together. It was probably the most difficult thing I've ever done. In that clinical, alien place Mum was just a body. A body with problems. No one there knew her for the capable, vibrant woman she really was.

On this day, the one that concerns you, Dad wanted to take a gift in to Mum. Her bedside was already full of flowers, so he asked me to buy a pretty dressing gown on my way home. It sounded easy. I popped into Marks & Spencer, remembered the right size, and managed, after much uncertainty, to make a choice between the predominantly pink and predominantly green. Then I found there were two lengths. And I froze. It was one choice too many. I couldn't do it.

All the sadness and uncertainty of that week came together and enveloped me, and I was rooted to the spot. I looked at my watch. I had only just enough time to make the purchase if I was to get back in time for Dad to have his tea and take it to evening visiting, as he wanted. The more I became aware of the minutes ticking past, the more my hesitation grew. Did I want the long one or the short one? Suddenly I was beyond the point of being able to make a decision at all.

Then you arrived. You looked like any ordinary busy woman, with a full shopping bag on each arm, taking the short cut through the store, from the shopping centre to the street. When you came up to me staring fixedly at the dressing gowns, you nodded cheerfully and said: "They are pretty, aren't they?"

"Yes," I replied wretchedly. "They are very pretty, but I don't know which length to get."

How did you know I was desperate? What was it about me that made you put down both your shopping bags and inspect the rack as though this was the most important decision of the day? We discussed size and colour. I told you why I needed it. Then you carefully, thoughtfully said: "Well, is there any chance your mother might be in a wheelchair?"

"Oh yes," I replied, "they put her into one every morning."

" Ah," you said very definitely. "Well I do know that the long one is too long for anyone in a wheelchair."

I thanked you and rushed off to buy the short, pink, size 14 dressing gown. I didn't see you after that.

I often wondered later, were you just an ordinary shopper? Or were you really an angel in disguise?

What I do know is that you enabled me to pick myself up, and carry on to deal with the most difficult days of my life. I've often wished you could have known that. Sue Hunter