Bit of builders advice please

Well the house was stripped to the bare bones and there was no sign of the other end so I'm pretty sure it goes straight into the concrete slab that makes up part of the floor in the lounge. Certainly heads that way.
I think that this was a drain used for something or other, became disused and they capped it. The area around the drain came loose over time and has resulted in the leaks so I'm pretty sure I'm OK to cap the drain again.
Might come back to bite me of course!

 

Which is exactly what I said I think happened... I have no idea what it might have been used for originally but it certainly hasn't been used for many many years. There is definitely no source (sink, waste, etc) using that exit point so it is just a redundant piece of piping now.

And it's now plugged up

 

It sure doesn't look pretty but the hole above the drain filled part filled with gravel then sealed over with mortar and the drain pipe was stuffed with some plastic bags and hardcore then sealed over with mortar. Very steep slope to it so any water will run off.
Once it's all dried off I'll keep the area clear so no further issues with damp hopefully.

 

But that wouldn't matter as there's no sink and no drains now... It's just a pipe