Steel frame, Thomson elite stem. I can turn it round, not up and down.

I can’t for the life of me remember the special ways to get it out.

Fire?

Seapost in vice, pull/twist frame.

Coca cola

http://www.theseatpostman.com/
Twisting it with too much force will split it.

If you can twist it it’s not really stuck.

Strip down to the frame, fit saddle, lie down on your back holding the frame, put one foot on the down tube and one on the chain stays, then heave and turn at the same time.

Or put seat post in a vice and do it upside down.

Exactly.

Saddle off, block of wood and a Birmingham screwdriver to knock it in.

Try undoing the bottle cage screws on the seat tube…

screwfix penetrating oil did the trick on a 30 year old post… be patient first.

Don’t risk your frame or even your seat post

Here’s your answer
http://www.theseatpostman.com/

If its moving its not an issue

Plus gas or penetrating oil. Spray daily for a few days from top and through bottle cage bosses. Twist out slowly by twisting saddle. Can stand on it and twist frame. If its moving you aren’t going to snap or damage anything