As far as I know the leash rule only applies to where there's traffic. Where these cycle routes are there is no traffic, just cyclists, pedestrians...and dogs.

It wasn't so much the dogs, they were doing what dogs do, sniffing around at the verges, it was the owners who wouldn't get out of the way. Still, I enjoyed the run and will explore other routes tomorrow. Hope the weather stays dry. It lashed with rain this morning and part of the afternoon, then the sun came out and it was really pleasant.

I'll take my camera next time and post some pics.