In the south-east window of St. Mary's Church, Lambeth, there is the full-length figure of a pedlar with his pack, his staff, and dog. This is the portrait of the unknown man who gave Pedlar's Acre to the parish of Lambeth. The story of the gift is worth telling. In the year 1504 a poor pedlar, passing over a piece of waste ground near the river, sat down on a tree to rest. While seated here he noticed that his dog acted very strangely, busying himself in scratching the earth with his feet, and smelling and barking about; every now and then running up to his master and looking him earnestly in the face, and trying to drag him from his seat.
The pedlar did not at first pay much attention to the dog, but its repeated barking and running to and fro compelled him at last to see what the animal wanted. Going to where the dog had been scratching, he was surprised to find something shining below. Digging on the spot he found a large sum of money, with part of which he purchased the land known as Pedlar's Acre, but which is now called the Belvedere Road, in Lambeth.
Maitland, the historian of London . . . (adds) that the pedlar left the piece of ground to the parish on condition that his portrait and that of his dog should be perpetually preserved in painted glass in one of the windows of the church. I cannot say whether this be true or not, but such is the legend, and there is the painted window, with the portrait of the man and his dog as evidence still remaining.
-- from George Frederick Pardon, Dogs (London: J. Blackwood & Co., 1857?) pp. 237-8. St. Mary's Church is now the Garden Museum in London. Its collections include the Vegetable Lamb of Tartary, once thought to be a cross between a vegetable and an animal. World War II bombs blew out the original Pedlar's Window, but there is a replica in its place, and no photos easily to be found! But you can get an idea of it at this blog.