Martin. That pipe is the exit from the breather system. Oil vapour and oil will come out here. Some people arrange for the pipe to exit onto the chain and act as a chain oiler. Early bikes had a P clip to hold the pipe next to the sump plate, so drips go on the ground. Later bikes only have a small tube, finishing above the chain. The tube was eventually discontinued on later models.
A little bit of a drip is to be expected with normal use, but if there is a constant stream of oil then that is the first sign of a problem.
Nice picture, told the story. The tube needs to be supported, and looks as if someone has already cut it short. It just pushes into the crankcase, seal in place with Loctite. Plenty of pictures around showing how it should be.
Swarfy.