In article om,
newshound writes

Looks a bit like an iron waste pipe to me; don't recognise the collar at
all. What happens outside? One option might be to fit a new plastic pipe
through the wall to an existing iron stack outside (which is what I
have). Then you can have nice modern unbodged pipework inside the house.

Agree it is likely cast iron, I have seen one with a similar collar from
a 60's build, the collar was sealed using lead wool compacted with an
offset compacter/chisel type tool.

I'd cut it off 2" or so from the wall to get a lower entry and use a
flexible pan connector to mate with the inside of the pipe. They're
meant to be self sealing but I'd add sanitary silicone to the
compressible vanes to make sure.

No need to disturb a cast iron stack in good condition, it should last a
century. Hopefully the building is not 99yrs old ;-).
--
fred
it's a ba-na-na . . . .