I brazenly stole this picture from an online humor site.  In all likelihood it was taken in Wales, in one of a series of deep valleys nicknamed the Mach Loop.  It’s frequently used by RAF and USAF crews practicing low, fast flying.  That, in turn, makes it popular with photographers equipped with telephoto lenses who perch on the valley sides waiting for opportunities like this.

Obviously the WSO in this RAF Tornado anticipated the photographers…