How to chose a behavioural therapist for my dog?

[GinBunny]

Hi all, will bump in the morning if I can but would really appreciate advice on how to choose a behavioural therapist for my rescue dog. She isn't settling in well and due to her background we really need a behavioural therapist rather then a trainer. But I don't know where to start.
Our vets haven't really been able to help and neither have the rescue. I don't want to go into details of why they can't help or what the issues are because that's a whole different thread - but for now, how do you find out who is best to help? We've found one who has lots of positive feedback but doesn't seem to have any qualifications. And another who seems to be well qualified, but I don't know what her qualifications mean - they seem substantial and she also has good feedback but I want to get this right. I just don't want to make the wrong choice for our dog, or us, she needs proper help.
Any advice very gratefully received (oh and any recommendations in SW London or Surrey even more so...)

Morning, just dropping by to bump

I found mine through the association of pet behaviour counsellors website.

this is where you need to look. I found a behaviourist through this site and was very impressed. She came out and spent a few hours with me and ddog, followed up the visit with emails and loads of extra information.

I am wary of people who set themselves up as dog trainers/behaviourists without doing any of the qualifications.
Several people recommended an 'amazing' trainer locally to me, and I found out that not only does he have no qualifications, but uses shock collars for recall training :(

Thank you both - that is really helpful.
The person that has the qualifications that I mentioned in my original post is a provisional member of the APBC but not a full member. Would you accept that or go for full membership only?
Bubble, that is awful but doesn't surprise me. I've come across a few that seem to sell an awful lot of the products they recommend as well.

What part of the country are you in?

Bubble has made a good place to start. I have been through the mill with trainers and behaviourists and found solutions with breed-specific problems. The issue is complicated by us keeping working dogs and dogs as pets. I keep working dogs as pets, but they still have to be treated as though they are working so I have been trained to treat them as working dogs although they still have access to all the furniture with us and cuddles. There are show dogs and working dogs and any-dog. When you contact these people, you need to feel a conection. If you look at the dog magazines problem pages, all the 'experts' are practicing and you can call them.

I've found someone on the site recommended above - so thank you. She seems very nice too and has good references on her site from vets etc and most important has worked with rescue dogs too. Surprisingly she is also the cheapest option - not that that was my priority, just an observation. So, vets coming tomorrow and will get a referral then we can start rehabilitation. Funnily enough, she's been on her best behaviour tonight! She knows...