This bird looks also perfect to me for a Northern Goshawk, the silhouette is simply the best feature, a long neck, the base of the tail is really large, and the edge of the tail sligtly rounded, the wing very long and well pointed (should be more rounded in Eurasian Sparrowhawk), and this bird has a really heavy breast, it is quite obvious in many of the picture.
The ear covert are also really dark.
I've seen Northern Goshawk quite often in France, and if this one is not I have to review all my past sightings :-)
Some information from the observers on how the bird was flying could be of good interest also, it is quite distinctive.
It's really a great find, congratulations.
Jonathan
