Many thanks for your replies (and what lovely dogs you both have too!).
I do already walk Brandy with a muzzle on as a precaution although I normally ues a soft (mesh) muzzle which does not completely prevent teeth coming in contact with skin (although it will obviously prevent the worst from occuring) - I do have a hard plastic muzzle for her too but I also have the bruises on my legs where she continually barges it into me to try and remove it. I wouldn't take the risk of not using the muzzle but I do worry slightly that it may serve to increase HER frustration of "not being able to guard if neccessary" and contribute to the guarding behaviour "if I have a go first then no-one will come near enough to become a threat"....if you know what I mean!?
I had a Barkbusters trainer come to us back in January and he taught us some techniques to use, including passive dominance (ignoring her attempts to gain attention, not allowing her to go through a doorway first etc), walking to heel with the use of a canny collar and water squirter and not allowing Brandy to guard the door. We had initial success with the techniques but it wasn't long before she was edging ahead on her walks again and ignoring us outside. She has also now taken to barking when we answer the door and seems to have become virtually de-sensitised to being squirted with water. The trainer has been back a couple of times and I have in fact booked for him to come again next Monday so hopefully he can straighten us all out again. The trouble is that he has a very busy schedule and would not be able to manage several repeat visits in a week although I feel that perhaps this is what we do need. I will report again after Monday's training, hopefully with positive news!
I did also try a "crackers" class for a number of weeks but didn't really feel that we were making any headway there (and she nipped one of the trainers there which was really embarrassing!).
I have also looked up intensive 3 day courses where you and your dog go - there is one run by Lynn Davies and instructors that she has trained up (from Dog Borstal) and I was wondering whether that would be a better option for us??? It's quite expensive though and not until September and I really need help now. Her methods on Dog Borstal seem quite effective so perhaps I should book this up and battle on the best I can until then?.........
I have also looked at Stan Rawlinson's website (dog listener) and wondered whether he might be worth contacting!?!...Although, having purchased his invention "the jingler" I have not managed to move on past the stage where you get them to ignore food until you give the go-ahead - She is brilliant at this (don't even need the jingler for that) but can't/won't seem to respond in the correct way with the sit/stay command (you have to keep them on the lead and rattle the jingler if they move after you have given the stay command as you walk away. I am persevering with this but so far without too much success!!
Thanks again for your advice - will keep you posted on any progress we make
Hazel