Control Your Dogs
by Chris MacDonald
Here’s another from Samantha Brennan. This time it’s a sign posted near a walking trail in Yorkshire, UK. It’s noteworthy for its politely conversational tone, as well as for the fact that the sign conjoins an injunction — “please control your dogs” — with a handy suggestion for how you might go about doing that (by keeping your dog on a leash).
Normative Signs: The Poetry of "Ought" 
But it doesn’t say “leash” is “lead” british for leash?
Yes, that’s my understanding. (It’s also the words North Americans use — at least sometimes — for the “leash” that you use for a horse.)