I had got compassionate leave and was travelling north with my sister and three-year-old Angela to see my mother. I was in sole and uneasy charge of Angela when I noticed that across the saloon carriage there were three airmen with the flash "Poland" on their shoulders, one of whom was staring intently in our direction. I followed his gaze and found that he was looking at Angela. After a moment's hesitation he got up, came across the passage, smiled at Angela, and handed her a block of chocolate. She was lady enough to say "Tank you" in a small voice, and then the Polish airman – a corporal – went back to his seat. When my sister came I told her what had happened, and she went across to the corporal to thank him. He blushed and his English was very self-conscious as he tried to say: "That's all right; I have two children myself." Then I heard my sister telling him: "My brother has been in Poland for three years – prisoner of war." The corporal's face lit up, and they all three waved to me to join them. I went and my sister returned to her small daughter.

They began to speak to me in English, but I could tell that they were uncomfortable in it and asked them in German if they spoke the language of our enemies. They nodded excitedly. "But we don't like to speak it. [If] we happen to use it here people look accusingly at us as though I were Hitler himself and my two friends Göring and Goebbels."

The first thing he said was "Where were you a prisoner of war?" And when I said, casually enough, "Posnan" I thought the corporal was going to leap over the table to embrace me. He turned to his friends, his eyes shining. "Posnan!" he exclaimed. "I come from Posnan!"

After that he could not speak fast enough for all the emotion he felt. He had not seen his native town since those black days of September 1939. His face clouded as he asked hesitantly, "And how are they going on, the people at home?" I could not tell him they were living on the fat of the land. But I could tell him that some of the people of Posnan are among the bravest I have ever seen.

The corporal told me that he had not had any message from Poland all the time he had been away. When he had said this he became suddenly silent, and the conversation lapsed. I was just going to return to my sister and Angela when he blurted out: "Do you know X street in Posnan?" I did not need to recollect. "Know it! Why, I've shovelled snow off X street many a time." He looked at me and lowered his gaze again. "When you were in Posnan," he said, "did you ever notice in X street two little boys, one about six and one about ten, both with blond hair?" My mind flew back to that street where I had spent many a cold winter morning with others from the camp. I told him that I did not remember two children, but that there was certainly one boy of about ten we had seen often because his fair hair marked him out from the others. I said, too, that we had often spoke to him and given him chocolate from our Red Cross supplies.

I suppose that if I were writing fiction this encounter would be justifiably condemned as incredible. This Pole had given my little niece a piece of chocolate, and it was all Lombard Street to a penny orange that I had done the same for his son in Posnan. The trials of the long years did not seem severe at that moment, for I realised as never before how truly we were together in a common cause. A child in a Polish city street – and a child in an English train. It is something to think about.