many significant archaeological discoveries, not the least being the identification of six new Roman marching camps between 1954 and 1972. Of great significance for the future were the trials which the Commission made in the early 1970s of the use of vertical aerial photography to speed up the survey of nationally important sites: of the Pembrokeshire hillforts Gaer Fawr and Carn lngli in 1973, and in 1974 of Carn Goch, a hillfort in Carmarthenshire. The methodology was also adopted for the medieval site of Cefnllys Castle in Radnorshire. Staff The Commission's staff was active in the wider archaeological world in the post-war period. Hogg had a fruitful partnership with the castle historian, D. J. C. King, to compile lists of early castles and masonry castles in Wales and the Marches. He and several colleagues collaborated to publish the reports of pre-Second World War excavations at the hillfort of Pen Dinas, Aberystwyth. The fourth secretary of the Royal Commission, Peter Smith (from 1973 to 1991), had joined the organisation in 1949 after a brief period as a trainee architect during which he became disillusioned with the prevailing modernist trend in architecture. At the outset his principal aim was to continue with the Glamorgan inventory, and five massive volumes were published between 1976 and 2000 which were highly praised - though even as the millennium ended the plan had not been fully realised. At the same time progress was made on the sites and monuments of Brecknock and a revision of the Radnorshire book of 1913 was begun to bring it up to modern scholarly standards. The chairman of the Commission, W. F. Grimes, encouraged greater interest in industrial remains - though he himself was a notable prehistorian. Particular attention was given to the early communications systems of the Swansea valley: a prelude to more extensive studies of Wales's canals and the remains of the Swansea region's industries. In the post-war decades the Royal Commission had consistently supported the county history movement in Wales, and in due time practically all the volumes that appeared - and continue to appear - in the series of histories of the counties of Glamorgan, Cardigan, Pembroke, Merioneth and Monmouth have drawn on the Commission's archive for illustrations and, in some cases, on its staff and commissioners for chapters. On the other hand, the Royal Commission's role in excavation was bound to change from the 1970s onwards.