Old slates from the roof of Ickworth House Suffolk

Last year at great expense the National Trust had all of the slates covering the great dome in the central part of Ickworth House replaced. The old slates had been in place for a couple of hundred years (I think) and were well past their sell-by date (ie I guess there were leaks). They were replaced by slates from the same place, the Lake District. The old ones have been made available for people to take away (preferably in return for a donation. These four I have got illustrate how roughly formed they were: and see that they are all of green slate. I'm not sure what to do with them, but there's no rush - an idea will crop up in due course I'm sure!