Sitting Pretty

....... a Green Veined White enjoying lunch on the buddleia :-)

Can anyone identify the plant in extras? It has popped up in the garden and seems to be growing quite quickly ( although most things are after all the rain ). It seems to be just a single shoot at the moment, so possibly some kind of tree? and it’s about 2ft 6ins tall at the moment.
It’s going to be dug out but I would just like to know what it is :-)