My mum and dad have a cast iron bath with a rigid over flow and a copper trap from either just before or just after ww2.

We tried to removed the waste and overflow to fit a sprung combined waste and over flow. the over flow was disconnected no problem and the new one fitted but the waste will not come out! I dunno what to do now

The nut underneath was cut off as it was ceased from about 60+ years of not being used. but even though its all flush the waste just will not come out.

Help please!!!!!!