Damsons make a fine fruit syrup. It’s the philosopher of fruit syrups: it’s deep.
To make a damson syrup you take some damsons, extract the juice and cook that juice with sugar.
By regulating the temperature at which you cook the damson and sugar mix you can produce a thin or thick syrup. The higher the temperature, the thicker the syrup, and so the more viscous it is, obviously. And the more viscous it is, the more it will cling to, for example, vanilla or nut ice-cream, duck, venison or anything else you would like to glaze with the rich flavour of damson.