This is one of a few species of Ammophila (the thread-waisted wasps), probably (but by no means certainly) Ammophila nigricans or Ammophila procera. They are difficult to identify, particularly from photographs and in this case, my photographs don’t show some of the distinguishing characteristics. In any case, this is one of only a few I’ve seen this summer. The wings are hiding the long, thread-like petiole, but it’s quite distinctive. I managed to get three decent pictures of this one before she flew away (I’m guessing on the sex—the orange is paler on the males but without them being side by side, it’s not always easy to tell).