Four panel paintings -- which represent the Annunciation, Praying Donor, The Nativity, and the Death of the Virgin, dated ca 1458 and attributed to a Flemish or Hispano-Flemish master-were examined by means of IR reflectography, x-radiography and micro-analysis. Numerous illustrations provide representative examples of the extensive underdrawing. Microanalysis of paint layers indicates a minimum use of transparent layers applied over opaque substrates. This characteristic, and the form and manner of execution of haloes, suggest the likelihood of a Spanish author for the panels.