Herring Gull chicks have hatched

I think these chicks have hatched in the last couple of days (they're on the roof opposite our house). You can only just see them peeping out once or twice from under their parent, who's holding their wings to make a wall to keep them in. Interesting that when it stands up, you can't see the chicks - I'm guessing they're keeping down low, as you can see the parent peer down at them.