After chasing Ruby all over the local park for days now (such a naughty girl) I have decided she needs to be on lead just like her brother Oscar (also a naughty dog - well, as far as recall goes). So I hatched a plan that might work and not pull my arms completely out of their sockets!!!
Two collars, one coupling chain and one extender lead. As you can see from below it was a rousing success (if you don't count the few incidents where Oscar and Ruby looked like a Push me-Pull me). I haven't given up altogether on off-lead play but I'm giving my stress levels a time to lower!!!