The Garden House, Buckland Monachorum, Yelverton PL20 7LQ(tel: 01822-854769) is open daily until October 31,10.30am”5pm; admission, £3 ABOVE The remains of the sixteenth-century gatehouse are cloaked in Campanula poscharskyana. BELOW The lowest of the four terraces in the walled garden. OPPOSITE Thriving in the damp climate, wall pennywort seeds itself widely ANTHEA GIBSOIM: I designed the courtyard, two terraces and two private gardens. Gardeningb There were fundamental differences from the conventional private commission, in dealing with which Mark Sumner, a landscape architect, was an invaluable help. He picked up on anything outside ordinary garden planning”for example, vents for the boiler. We were not bound by historical reference; but one constraint was that the courtyard is over a car park which meant there was no possibility of planting in the ground. However, I felt that.