Yes, the recumbents show up well in the picture.

It looks too modern to be a stone circle, to be honest, although it is clearly something isn't it?

Also, that area of the Peaks has been pretty extensively mapped and investigated over the years, so it would seem a bit to obvious for it to have been missed.

Be interesting to see if any old large scale maps (25") from the late 1800s/early 20th century show it any different before it fell down?