John can't help grinning. Whatever their quarrel, Will's conversation about his dog - it is his dog whatever the man might claim - had been entertaining. The use of the word 'hound' does catch his attention, though. It's a reminder of his and Sherlock's last case, and decidedly less friendly 'hound' than Deoji or Julien's pets might be.

"The good ones are, anyway," he agrees with a nod. "Had a run-in with one that wasn't particularly friendly not long ago. You said your father's 'hounds,' though? Was he into some sort of sport? Fox-hunting?"