I think it is Silver Birch trees (Betula pendula) growing between the west end of Greenwood House and Herrison Hall, and again the other side near the east end of Redwood House. They have fine elegant drooping branches borne on a trunk with a characteristic cracked white bark. In April as the leaves begin to open there are dangling catkins too. On my evening walks I look up into the gently waving foliage and gain a sense of calm; and I like the patterns that they make silhouetted against the sky.