The illustration is reversed in print

The 1902 catalogue of paintings in Penrhyn Castle records that [The painting] was bought about 1850 by Edward, Lord Penrhyn, from Mr. Scoltock who had bought it while travelling abroad. Lord Penrhyn gave about £100 or £150 for it, and never cared for it at all. In 1899, being in a bad state, it was found necessary to transfer it from panel to canvas, when it was discovered that the picture had been much repaired some time ago, several white patches appearing where the paint had been restored, but the heads and figures and all important parts of the picture were intact.
What was Wolfflin doing in North Wales?
Dieric Bouts the elder was trained in the studio of Rogier van der Weyden.
Saint Luke painting the Virgin Rogier van der Weyden 1435 (Museum of Fine Arts, Boston).
Saint Luke painting the Virgin Jan Gossaert 1527 (Kunsthistorisches Museum, Vienna).

This is going to take some sorting out.
Rubens served as court painter and diplomat to the governors of Flanders, Albert and Isabella of Spain. After her husband's death in 1621, Isabella commissioned Rubens to design twenty tapestries for the Convent of the Poor Clares in Madrid. The subject of the tapestry series, woven in Brussels and still in the Spanish convent, was The Triumph of the Eucharist. The Meeting of Abraham and Melchidezek is part of the series.
This engraving by Witdoek is based on an sketch by Rubens (Wallraf Richartz-Museum, Cologne). A related sketch is in the Musee des Beaux Arts, Caen.

This magnificent picture is one of the cartoons for The Triumph of the Eucharist tapestries. All the cartoons are in the Ringling Museum.
Rubens made a large number of sketches for the series - Fitzwilliam Museum, Museo del Prado.
There is an oil sketch of the Ringling cartoon in the NGA, Washington.

Agostino has developed ideas from Botticelli's Last Communion of Saint Jerome (New York).