wrote:

Two generic types of paint remover - caustic soda (sodium hydroxide)
or nitromors type [...]

I was incredibly sceptical, but Mum bought a can of "Home Strip"
and left it at my place and I figured I might as well give it a
try. I'm a complete convert and certainly would give it a try in
this situation - slap it on, cover it with tin foil for an hour and
then remove it and it takes all the paint with it. I've used it
now on some pretty horrible surfaces (quite like the one the OP
describes) and got back to lovely clean oak.

The company only ever seems to describe the ways other products
work and never how their own ones work, which opens up the path for
understandable scepticism - however having used it I confirm it's
worth a try.
http://www.ecosolutions.co.uk/Home-BaseA.htm
--
Selah