Black Redstart

I was not aware either, yours looked more like the European Redstart, so I did some checking. Take a look at some of my Black Redstart Spottings, you will notice they are very different to yours. http://www.projectnoah.org/users/Malcolm%20Wilton-Jones then type "Black Redstart" in the search box and click "Search".

This eastern variant is very different from the western variant which is overall black except for the red tail.