Painting of the day

Professor Michael Wheeler gave a fascinating lecture about some of the Italian paintings described by John Ruskin after his visits to that country in the 1840s. One was this depiction of the Marriage in Cana by Giotto in 1305. This is the first miracle in St John's Gospel and is not mentioned in the other gospels. The wine at the wedding (of persons unknown) had run out and when Mary pointed this out to Jesus, he instructed the servants to fill six amphorae to the brim with water and to take them to the governor of the feast. When the governor had tasted the contents, he expressed surprise that the family had kept the best wine until such a late stage at the wedding feast. You can see the servant pouring the water into the amphorae in the right corner, the comic figure of the governor drinking the wine next to her, with Mary looking on from behind.
There was some discussion about the other figures in the painting. Ruskin says the central figure in red is the bridegroom and that the way in which he and Mary are holding up their right hands is symbolic of the Eucharist. However, it seemed to some of us that the figure is a woman, not a man, from the way its robes are flowing and the fact that its hair is tied up in an ornament. From the left hand side of the table there's Christ, the bridegroom, a sacred figure in a halo, the bride and the person in red. Traditionally, the other sacred figure at the wedding was John. However, the figure in this painting is of an old man with a grey beard. Joseph was raised as a possibility but ruled out as he's not mentioned in the story nor in St John's Gospel. An interpretation that was raised was that the central figure in red is The Church, the bride of Christ, and the elderly man could be God, the father.
Above is an azure sky and what could be a holy vessel is positioned above the central figure: another symbol of the church. One could then say that to reach the azure heaven, you need to go through the dark doorway on the right. Christ faces that door: is it a foreshadow of his crucifixion?
Another interpretation put forward was that the central figure could simply be a portrait of the person who commissioned the painting.
What do you think?