It is an outside pipe to an old toilet that has been removed only they didn't seal the pipe...

Gaynor, October 2009

try kevs answer or get a lead lock fitting and a blank cap.
The problem with lead is it is all sizes you will need to take section to the plumber merchans to get the right fitting.Or get a OLD plumber in who can wipe a lead joint on to copper watch and marvell as that was once who all joints were made

erj, October 2009

In the mean time you can try flattening it with a hammer. Not recommended as a permanent repair but it keeps your feet dry.

kev, October 2009

You connect the lead pipe to a modern plastic pipe called MDPE with a coupling called a 'leadlok'....and then a MDPE stop end is fitted to that which stops all leaks. So - lead pipe, then 'leadlok', then short length of MDPE pipe, then a stop end. Done!

John, October 2009