Copyright troubles

[frualeydis]

I'm working on my article for NESAT and one thing I need is the permission to print copyrighted material. Well, since copyright usually ends 75 years after the death of the creator (100 in some countries) and the painters concerned in this case have been dead for at least 700 years i can't see that I need a permission from anywhere. But I don't think the british publishers share this view. The problem is that one of the institutions who has important images won't answer their e-mail so now I don't know what to do. The images are really important to the article and it is stupid that an institution should be able to stand in the way of research (in this case it's the Pierpont Morgan library). It's not like it's a commercial publication.
But I know that there has been some court rulings about this, the copyright claims of museums vs the original meaning of the copyright law and I remember reading about this in articles of the internet.
And this is where I need your help: any links?