I have a piece of rootstock from my neighbours Victoria plum tree (you dig it up and it's yours). I've let it grow for a couple of years; it once produced some small green sour fruit. I've swotted up on bark grafting over winter and assembled a special knife, grafting tape and sealing paint. Today I've grafted scions from a damson on one side and Victoria plum on the other. All the bits have just started to bud so I'm crossing my fingers!