Simon Marmion, 'A Choir of Angels: From Left Hand Shutter', about 1459

These two paintings – The Soul of Saint Bertin carried up to God and A Choir of Angels – were once the upper parts of the wings of an elaborate altarpiece that was made for the high altar of the abbey church of St Bertin at Saint-Omer in northern France. It was commissioned by Guillaume Fillastre, Abbot of St Bertin, and was consecrated in 1459.

The wings are thought to have been painted at Valenciennes, where Simon Marmion was almost certainly the leading painter; he had moved there from Amiens between 1454 and 1458. Marmion was also well known as an illuminator – according to the sixteenth-century historian Jean lemaire de Belges he was the ‘prince of illuminators’. The style of the wing panels is very close to that of some of the most beautiful manuscripts of the 1450s, made for Guillaume Fillastre and presented by him to Philip the Good, Duke of Burgundy. Many of the manuscripts in this stylistic group can be shown to have been made in or near Valenciennes. There is no proof that Simon Marmion painted the wings of the St Bertin altarpiece or the related manuscripts, but there is a great deal of circumstantial evidence in favour of this theory.

The main parts of the wings are now in the Gemäldegalerie, Berlin. On the inside these show Fillastre himself with scenes from the life of Saint Bertin. On the outside are biblical kings, prophets and evangelists, painted to look like stone statues, on either side of an image of the Annunciation. The central section is known only from written descriptions, but was in the shape of an inverted ‘T’ and was made of gold, gilded silver and copper, rock crystal, diamonds and other precious stones. It had three-dimensional figures of Fillastre and Saint Bertin, and scenes from the life of Christ. All the statuettes were gilded but with faces and hands painted in flesh colours. At the top was a gilded Tree of Life surrounded by angels and topped with a pelican feeding her young (a symbol for the Passion). From the Tree of Life hung a golden dove, in which the Host – the consecrated bread of the Eucharist – was kept.

Fillastre was an important man. A favourite of Philip the Good and Charles the Bold, he was successively bishop of Verdun, Toul and Tournai. In 1447 he became abbot of the important Benedictine Abbey of St Bertin and was an active patron of the arts. Many of the records of the abbey have been lost, but surviving accounts list four payments for it. The total cost was over 1895 livres Artois or pounds, an enormous sum, especially as the precious metals and jewels came from the abbey treasury.

The altarpiece and its shutters remained on the high altar until 1783 when it was moved to another part of the church. They were still there in 1791 but the central section was destroyed soon after and the wings passed into the hands of a local baker, and from him to a local art-lover, perhaps the painter Louis Francia. The fragments here were separated from the main portions by a nineteenth-century dealer and bought by the National Gallery as part of the Beaucousin Collection in 1860.