Images of saints were an important devotional aid in the medieval period, and were found throughout churches, not just in the stained glass, like the Boppard panels, but also paintings, sculpture and other art forms. They were popular in public and private worship as a tangible connection to the saints during prayer. A good example of standing saints in other art forms in the Burrell is the retable, below.
A retable is a framed altarpiece that is placed just behind and perhaps slightly raised from the altar. This retable is from Burgundy in France and dates to around 1450 to 1500. It shows Christ on the cross (a direct link to the Eucharist, the central focus of the medieval mass) with the Virgin Mary on his left and John the Evangelist on his right, with four other saints. Each saint is shown with their attribute, to illustrate who they are. The retable would originally have been beautifully painted, only traces of which are now left.
John the Evangelist is usually regarded as the same person as John the Apostle and John of Patmos, who wrote the Gospel according to John in the New Testament. He is seen here holding his book.
St. Peter is next on the right. He holds what is left of a key (the key to heaven) in his left hand and an open book in his right hand. It is generally agreed by scholars that Peter told his memoirs to John Mark of Rome, who then wrote the Gospel of Mark.
Last on the right of the retable is St. Andrew, the brother of St. Peter. According to tradition, when crucified, he asked to be put on a Crux decussate, an X-shaped cross, or “saltire”, as he was unworthy of being crucified on a similar cross to that of Jesus.
To the left of Mary stands John the Baptist, holding his attribute, a lamb, and wearing the camel-skin coat of the Gospels.
Originally, I said that the saint on the left was St. George and the dragon, but Malcolm Shaw, a Burrell guide, has pointed out that it is not St. George, but more than likely the Archangel St Michael fighting the devil. The image below is “The Archangel Michael as the Weigher of Souls” by Hans Holbein the Younger, painted in the early 16C.
Boppard Conservation Project - Glasgow Museums 