From 1834 Clayton began buying land to preserve the Wall, now a World Heritage Site, which was subject to the removal of stones for reuse. He had some restoration work carried out on parts of the Wall. He helped preserve that central stretch of Hadrian's Wall that includes Chesters (Cilurnum). Housesteads and Vindolanda, and carried out some of the first archaeological excavations on the Wall. His first published work, in 1843, was his excavation of the commanding officer's bath-house at Chesters. He was involved in excavations most years for the next half-century, both at Chesters and elsewhere along Hadrian's Wall, namely Cawfields (Milecastle 42), Castle Nick (mc 39) and Housesteads Crags (mc 37), Housesteads and Carvoran. His archaeological work continued into his later years, and he was in his early nineties when he uncovered the spectacular sculptures of the temple to Mars Thincsus at Housesteads.