Apologies for not updating. We have been awaiting assessment by two behavioural experts, one of which is a vet and the other a dog trainer (both registered and costing an arm and a leg each
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Both have concluded the same thing, he is a very nervous dog who is running up to things he does not like and barking out of fear...a bit like a get away from me type shout. From what I'm told he wasn't attaching the man as such, more trying to get rid of him. Not that it makes it any better for the man but it's an explanation I suppose. I have not seen the man, but I have also heard nothing from him.
I have also been told it's very typical of the breed when unsound or incorrectly socialised, mouthy and shouty but secretly huge wimps.
I took him to the behaviouralists dog socialisation club. I felt physically sick as it was full of adults, dogs, puppies and children but she encouraged me along to see his reaction. Turns out once he settled he was actually very submissive and none aggressive and played with the dogs and people 
Granted, nobody touched him or interacted with him on strict instruction but he didn't go into a frenzied attack or anything which I was half expecting, watching him interact he was very nervous and did the bark thing to another dog...ran up and gave it verbal abuse and then ran away 
We also had a visitor to the home and let him in (under supervision and muzzled!) and be barked but actually left the room, he didn't attack or try and bite.
Walks have been okay, still reactive but that's nothing new. I walked him with the trainer in a busy area with 5 other dogs and he didn't react at all but at home he is still flying through the air barking like a mad dog at everything.
Saying that, I won't be unleashing and muzzling him any time soon that's for sure. I still know he is 100% not trustworthy.
So, in all its confused things more than before. On one hand I am happier in the sense that it seems it is a huge front he is putting on and that he is actually a wimp and has never shown any signs of following throug after the bark but then again I understand it's going to be a long slog, he is only 2 and I could have another 10 years of this 
The house thing I'm not all that concerned about yet as we can safely separate him. If he is to stay it means finding a new house when we move that is easily dog proofed (big enough for a secure run when people come round) which DH is keen to do. He did settle with visitors the other day and does so he could settle in the run with some training I hope but again it's speculation at this point!
So really no, I haven't made any decision as yet but we are making some progress and if it gets to the point where it's hopeless then I know what needs to be done and I am willing to do that