Got the seat post out of a 501 tube Raleigh, with time, a touch or Plusgas, some heat and a vice.
Only the cranks, headset and BB to go.
We’ve got a bit of kit at work which is a long metal bar with a hacksaw blade welded in to a slot. We can then cut the post lengthways to remove it. Obviously this is the last resort, but I was assured yesterday it works.