Does anybody have any experience of doing such a thing in the past? I
would
be grateful of some advice, particularly with regards to the materials
that
I should use?

I've seen it done with, as you suggest, a profile. But AFAICR it's done
in sections on a bench against a corner shaped former with scrim(?)
bedded in the plaster to give it strength. I can't remember how the
sections are held in place.

The other way is to make your new stuff from wood using a router and
home cut router blades. You buy a block - eg
http://www.screwfix.com/app/sfd/cat/...77439&ts=92326
and cut your own blades to match the existing profile. With that you
can make lots of new wood moulding.

I have no idea which is quicker / easier.


Regards, NT