I am in the process of re-doing my bathroom.

My bathroom is on the ground floor of a block of flats (old fashioned
Glasgow tenament for those familiar with Glasgow). I have 2 pipes
running up one of my bathroom walls and am able to identify one of the
pipes as my upstairs neighbours cold water supply.

There is however another pipe which is much older (its lead for a
start) and I havent been able to identify whether it is still in use or
not.

I want to determine whether the pipe is still in use or not. I have
asked my neighbours but they are unsure and cant identify where it is
leading to. There are no obvious signs that it halts anywhere and I
have lifted my bathroom floor and the lead pipe is connected to a
copper pipe under my floor. The copper piping looks relatively old too
and could well have been how the hot-water supply was provided prior to
the installation of a combi boiler.

Does anyone know how I can determine whether or not this pipework is
redundant so that I can remove it if it is?

Thanks,

Paul