The aim of the work is to distinguish the individual masters and their assistants on the basis of the preparatory drawing. The panel pictures in the Holy Rood Chapel were studied by means of photographs in the infra-red band of 850 nm and reflectography in the 1 micron band. Considerable differences in the technique of drawing and in the quality of execution were found; definitive conclusions can be drawn after the assembly of all photographs of all panels on the completion of restoration work. Reflectography provided certain details of the initial drawing were not recorded cy infrared photography.