"As for "if you MUST have an aggressive dog"...it's an occupational hazard with rescues. I didn't take on current PageDog because I was just itching for a life of muzzles, 5.00am and 11.00pm walks and shelling out on behaviourists."
Ah come on, you took him on on purpose just because you're antisocial 
Mine isn't a rescue, I've had the joy of watching my lovely friendly puppy slowly become aggressive despite me spending a small fortune and what probably adds up to months working with him.
All because other people can't or won't keep their dog away, they wouldn't do it when he was a small limping puppy on lead, they wouldn't do it when I was telling them he was on lead because he was recovering from his first operation, or his second, they wouldn't do it when I told them he was on lead because he has pain in his elbows and spine and can be a bit grumpy...they still don't do it now he's moved on to trying to hurt them before they hurt him and is wearing a very obvious muzzle, is snarling and barking before they get to him and I'm there standing in mud or bushes having left the paths to give them room to get past and tell them that he's aggressive.
But, yeah, it was totally a decision because I wanted to have to deal with all that and random strangers shouting abuse at me when he does in fact react exactly like you'd expect from a dog being walked on lead and muzzled as far out of the way as it can get attached to an owner warning them he'll react like that.
Not at all because I prefer to decide when my dog is put to sleep based on his medical state and not because other people don't control their dogs.