cord

Hello, I wonder if anyone can help with this. I have a radiator pipe that goes into the radiator, but just before that it splits off to a short terminated end that I assume would have been connected elsewhere long ago... this small end of pipe has some straggly 'thread' hanging off it. Perhaps...

There's either a sink or a bath either side of the bathroom door. Could I put a pull cord switch above the sink? Thank you Dain