Demotion

[sydlance]

I was employed as a Director of a company and signed a contract as such. Now, three years later they are trying to offer me a new position which would be reporting to a manager. When I pointed out that I am a director, the manager told me that the position is no longer active.
My question is that I have never asked for another position within the company. I am still doing the job which I was employed to do and I have never been told that my job is no longer active.
How do I stand within the law?
Can they demote me and appoint someone to my current position albeit with a new title?
I have signed no new contract at all.