Not all breed specific trainers are good (especially so with GSD's, some GSD people will always dislike white/longcoats and that can affect their opinions of individual dogs) - always check their qualifications/reputations first.
Be aware that any
good dog trainer will insist on a vet check FIRST, just to make sure that there are no medical reasons for the behaviour.
If your dog is insured sometimes the insurance will cover the cost of the behaviourist (especially if it is after veterinary referral).
This trainer looks good (from the COAPE site):
"Affiliate
Cath Schofield
134 Cherry Hinton Rd, Cambridge, Cambridgeshire, CB1 7AJ, United Kingdom
Telephone: 07866473504
Website:
Puppy and Dog Training in Cambridge and Colchester
eMail:
cath@wuff-online.co.uk
Information:
I offer puppy, beginner and graduate classes in Cambridge and Colchester. One to one training also takes place in Cambridge, Colchester, Braintree, Dunmow, Haverhill, Royston, Newmarket, Huntingdon, Halstead, Bishops Stortford and Stansted.
Behavioural work is also done in the above areas."
Sue