Right, Dan S. W., this quote was part of Walsingham's comment on the day he set the world record for grouse per one gun (or, to be more precise, four guns in the hands of one shooter). I think it was also the first day when he shot with his Whitworth steel barrels, and if it's so, than the explanation can be purely psychological. He expectedWhitworth barrels to be anyhow different from Damascus, and his brain was unconsciously 'programmed' to look for the difference, but since he found none in the way the gun handled, or the way the birds were falling, the brain registered a difference in sound. And if it registered as "unpleasant", then we may safely guess that good old Tom Grey had a prejudice against fluid steel.
That, or there was some defect in his particular Whitworth-barreled Purdey.
Whatever it was, the claim that "Whitworth barrels have an unpleasant sound" has spread across the globe, including Russia: Leonid Sabaneev makes it in his influential "Hunting Calendar" (1885) - without any reference to Walsingham, of course.
