we have Maxwell 3 month westie .. a hugh garden and cant let him off - our neighbour next door rescued a wild dog (now +7 puppies) - any chance Maxwell gets he will bite and snap through the fence at the puppies now 8wks and the mother ... which is scarey for me when the enormous mother snarles back - he is like this with any other dog he meets through a fence except for one who is a male wirehaired foxterrier who he loves to bits ... when he meets dogs face/face he barks but doesnt bite - is he protecting his terrority ? is there something i can do to make him more social?
i dont want him to have bad experiences of other dogs and try and keep him away from the fence.
advice please.

Since you have a huge garden, would it be possible to partition off an area for your puppy well away from the fence?

It's perfectly normal dog behaviour. All of my dogs look really aggressive if people look at them out the window or through the fence as they bark. Same with other dogs -in fact it's even the same with my OWN dogs if one is not with them! They'll behave aggressively towards their own if one is on the wrong side of the fence. If I were to let the dogs out or in, they'd behave differently instantly and be friendly. Your best bet is to make sure the dogs can't see each other through the fence.

I was going to say make the fence solid. 

If the garden is too large to do that all the way around then fence off the part closest to the house, and only allow him in the rest under strict supervision when the other dogs are not there.

The bad thing about a garden protector is that the thing they are protecting against(passerby or dog) always walks on past so the dog thinks they have done a great job and wait till the next threat approaches!!  I have a neighbour who had the same problem only with 2 westies.  They are relentless and annoy the entire neighbourhood with their barking.  But.. if the passerby stops and says 'shoosh', the stop barking and just watch you pass.  I showed the owner how to stop them and how he should ask everyone passing to take 2 seconds to do the same, but he wasn't consistant so they only don't bark at me. 

unfortunately they are an open weave wooden fence - we are about to move house and have 1 x rottie, 1 x 57 and a  cat as neighbours ... as i feel Max is trying to protect his property i`m planning to take him to the new house before he realises we live there and let him meet the new neighbour dogs - when we go for a walk and he meets dogs through their fences -  he is more polite....