Speed of magnetic force

[principled]

This may be an easy question, I'm not sure.
We all know that magnetism is quite complex (see en.wikipedia.org/wiki/Magnetism ), but I'm interested in permanent magnets and the speed that the magnetic force will radiate from a permanent magnet to another object.

Example:
We have a permanent magnet. Around it we have a barrier which the magnetic field cannot penetrate. Outside of this barrier at distance x we have -say- a ferrous mass. When we remove the barrier, at what speed will the magnetic force radiate out? What is actually being "radiated" and will this speed vary between a gas and a vacuum. If so, why?

I am aware that an electromagnetic field propogates at near the speed of light, but I can't find anything on permanent magnets.
P

[speakertoanimals]

A permanent magnet is just something that produces a magnetic field. Hence if you remove the 'barrier', the magnetic field can at most spread out at light speed.

think of it this way instead. Suppose we have a coil producing a magnetic field, because I am running a current through it. I am a long way away from the coil, and I have a compass needle responding to the field. Now I switch the current off, and the magnetic field collapses. How long before the compass needle notices?

Well, the switching off of the current is a signal, transmitted to the compass needle via the magnetic field. Hence relativity tells us that the fastest that signal can be sent is light speed.

It MAY get there slower, especially if I have some other substance in the way -- especially something that can be magnetised itself by a magnetic field!