To be fair I was expecting some issues with Whippy. She has had a few very bad experiences lately (1: pinned to the floor by a JRT who wanted to kill her while his owner laughed "He's only playing" 
2) attacked by another JRT we brought in as an emergency foster 3) Dry humped by an over excited shaggy lurcher, she did not know) and has just finished her season and has not been walked with the terrier for a while.
I found she was more confident being walked alone so I could concentrate all my attention on re building her confidence or with the Grey who she seemed to be calmer with and who was more confident than Devil is and so Whippy felt safer following her cues.
I was not expecting Devil Dog to be quite so well behaved. It seems he finally Gets It 
Event 1) We see a spaniel on an extendable lead. To be fair the Spaniel did actually do that much wrong. He was just a tad too far out on his lead and was making to apprach Whippy who was throwing out back off signals left, right and center. She eventually lunged at him, but couldn't reach him. I have her on a short lead for now. Devil Dog remained seemingly unaware of the Spaniel and Whippy's distress and continued eating grass.
Event 2) Another Spaniel off lead. Approaches slowly, watches Whippy's signals, ignores her. Approaches Devil. Greeting goes well. Whippy copies and greets the Spaniel. All is good.
Event 3) We spot an off lead pack of around 6 or 7 off lead dogs. I pull mine closer to me and step to side of the path, talking calmly to Whippy. Clearly indicating to the owners that we don't to interact. Do they understand? Do they buggery. All dogs immediately encircle us 
I ignore the terrier and hopes he behaves as well as he during events 1 and 2 and talk clamly to whippy to give her the signal everything is okay. All goes well, owners eventually get the message and call their dogs off. Devil behaved perfectly.
Event 4) A horse, Devil Dogs arch nemisis and most feared and hated animal. Last time we saw a horse he did his usual I. AM. BIG. DOG. FEAR ME routine, which resulted in the horse running at us and Devil taking off in the oppiste direction, which happened to be down a very slippery bank and into a stream. Dragging me behind him on my arse . We never walked that way again.
This time, he spots the horse. Hackles go up. I cheerily command him into a few games he knows, he goes along with it plays the games. He lets the horse pass paying no attention. I do my best not to pass out from shock.
Event 5) We see three of the 6 or 7 dogs we saw earlier. They still don't get the message and allow them to approach. The meeting goes to quickly for Whippy who starts barking and growling. The dogs ignore her warnings and try to approach her still. The owner has to come and retrieve it by hand. Devil Dog just stares at whippy looking quite alarmed at the amount of noise she is making and ignores the third dog sniffing his arse completely.
Event 6) Some eejit lets his very bouncy terrier out of the car unleashed, The terrier makes a beeline for Devil Dog and starts dry humping him. Devil actually plays along and joyfully joins in a game I can dry hump better than you can 
. It's all too much for Whippy who starts going nuts. Both dogs continue to ignore her.
Obviously I still have a lot of work to do to re build Whippy's confidence, but she is fairly easy going and until now has been very good with other dogs. I might take her out alone in the morning and let her off, she is much better off leash.
But what has happened to my terrier? T'is not normal. He is lulling me into a sense of false security in order to do something Really Bad isn't he?