Even if I hadn't seen this image before, as someone who's actually herded sheep with my collies, I see a some things that make this photo inconsistent with the caption. The biggest is that there are no sheepdogs. This is a darn complex series of shapes and to get anything close to it would require a lot of dogs and a bunch of handlers. It's hard enough to get sheep to stay in one roundish bunch let alone forming a series of letters. Heck to form the "P" would require a dog in the middle of the loop to keep it open. Finally, when herding dogs are holding sheep to a definite spot, the sheep are alert and looking at the sheepdog. The sheep in the photo are relaxed not focused on anything but something on the ground at their feet.

Though not Amazing Grace.