Digby doing the jumping thing is him telling you that he is insecure and not quite ready to give over the reins of leadership just yet.
It is a VERY good sign, in this case.
You have convinced him 98% that it is OK not to be the one with the stress and worry. That is fantastic!
He will still be feeling slightly stressed and is looking for reassurance - this is a puppy response.

You must understand that he is looking for reassurance and that you have to give him peace of mind, but in a way that reaffirms your position without leaving him unclear or stressed.
As soon as he makes the first hop up you stop dead still - arms, legs and body - still in the position you are caught in. As soon as he sits carry on as if nothing happened.
If this takes more than 30 seconds try crossing your arms and looking up into the sky. If you really get fed up of this before the dog sits you can turn your back on him and wait.

If you can anticipate the moment when he will start to jump then distraction is the key - give fast commands in a high voice with loads of, "Gooood booyyyyyy!!!" stuff. Go nuts!! Keep him interested in you and busy with plenty of reward - vocal and physical. Help him with some practice in the garden first and make it the most fun he has ever had! Really stupid voice and only things you 100% know he will obey. Make sure one of the commands is, "heel," for two or three steps only. After a minute or two of messing around get him to sit for twenty seconds then carry on walking.

This is really useful to do before you get to the walking at right angles thing. Make it a random part of every training session - you suddenly go nuts for no reason.....

The reason is - if you feel safe enough to go looney then everything must be fine, the pack has nothing to worry about, all is safe and under control enough for some fun but you are still calling the shots. This will make things feel better and safer for Digby. Things are soooooooo safe and fine that the leader can play, but Digby still knows exactly where his status is.

You have done a fantastic job already and it won't take long if you do nothing else for everything to settle down.

What I want for Christmas is clients like you!!!!!

I'm so glad I could help and hope you realise how great a job you have done.

My only regret, and not because I want to see S. Africa, is that I couldn't see you working the dogs.
I hope you feel proud of yourselves and I hope you see the change in your dogs' attitude to life in general.

Well done!