Candle in the wall

Another late night at work again, and so I was cycling home along the canal in the dark when I saw a glow coming from the wall near East Harrison Park. Someone has removed a large stone in the wall and placed a candle inside the cavity. It was burning brightly and was perfectly sheltered from the wind. It was strangely peaceful and there was no one else about. But who would go to the trouble of removing a large stone from the wall and placing a candle there?