How do i convert a List<Interface> to List<Class> in c#

I have an interface defined as

public interface IReaderInfo
{
    string Displayname {get;}
}

and a class that implements that interface

public class ReaderInfo : IReaderInfo
{
    string DisplayName {get;}
}

I then created a function which return List

public List<ReaderInfo> GetReaders
{
     var readers = new List<ReaderInfo>();
     var Ireaders = someobject.Getreaders();// Returns the list of IReaderInfo.
     // Now i would like cast Ireaders as readers and return.
}

How do i cast it?