Mr Smith walking his dog had heard a gunshot ? So there's nothing like the sound of breaking glass as well as shooting into the air,to arouse those in the cottages not far away. Or even the odd one or two who like a walk in the summer air. Farmers start early in the harvest time if the weather's fine.
And did Mr Smith say that the shot he heard definitely came from WHF, bearing in mind that it took some 25 shots to complete the job? In such isolation sound travels. It's very rural. There were likely to have been poachers. A shot being fired signifies nothing.