You shouldn't, in theory, need a long line.
Quite true - in practice however, a long line can save a dogs life
I think it is a very sensible option to use a long line in recall training, as you said Rachel you need to set up to succeed.
It is one of the hardest things I find to get through to my clients.
DO NOT call the dog unless you are sure of success!
If you do you will dilute the power of the cue.
Reward with a really high value reinforcer for a full thirty seconds if you can and always reward your dog with something it wants when it comes to you.
Tone of voice and praise are sometimes not enough.
I use 10 meter horse lunge reins from netto, it only cost me about 3 quid and is one of the most valuable training aides i have.
At 5/6 months dogs enter adolesence with allsorts of hormonal changes going on.
Dogs also enter a second fear response stage at this time where things that they have been ok with up until now can all of a sudden start to spook the dog.
Maybe something he reacted to spooked Dyllan?
remember as well that a recall learned in one location will not generalise easily to other places.
Train your recall in as many locations as possible, but remember always ensure it is happening or will happen before you use your cue and reward every time when the dog comes.
Make your dog feel that coming to you is the best thing in the world.
One of my tricks is to reward with half a roast chicken every now and again.
That seems to help matters