Casgliadau Celf Arlein

The description of the picture offered above ignores the top left-hand corner where, passing under two palm trees, the Holy Family is seen on the Flight into Egypt. Am I right in thinking that this detail is indebted to Durer's woodcut of The Flight into Egypt, ca 1503-1505, (Holstein 201) but with the direction of travel reversed? Durer's picture is remarkable, among other things, for presenting the Virgin, who rides side-saddle, with her back to us, and, instead of the drapery of her skirt that would have covered the flank of the donkey in a more conventional pose, we have the drapery of a saddle cloth. The result of posing the Virgin in this unusual way is that Durer's presentation of Christ is extraordinarily unconventional. All we see is the back of his head. I wonder whether there is any other painting of Christ in which Christ is so little visible. Thus Durer shows us a refugee family escaping from Herod's infanticide, aware of the dangers, and hiding the child protectively from prying eyes, including even those of people who examine the picture. Amico Aspertini copies these unconventional and original features from Durer, plus, of course, the entirely conventional iconography of Joseph leading the donkey, and the presence of the palm trees referred to in the apocryphal Gospel of Pseudo-Matthew. But I am perplexed by the riderless donkey / pony that seems to have replaced the ox that we might have expected, and by the identity of the figure who walks behind. Who is he? Can anyone help?
Incidentally, please let me register a howl of protest against the postcard on sale at the gallery. By trimming the left and right edges of the image it manages to exclude Joseph and thereby makes nonsense of the Flight into Egypt.

I believe this is one of wales greatest paintings