Poor Stanley.
I agree with Matthias' training advice. Does Stanley do obedience tricks like sit and others? You could take some really yummy treats and try to focus him on performing for treats. Do it sort of far away from people and in an area where he is comfortable. Or is he nervous anywhere outdoors?
I would also enlist friends to work with you on training. It can be hard working around strangers who want to run up and pet or hug your cute dog. Have the friend stand at a distance and ignore Stanley. Then have the friend move closer over time and do walk bys, all while ignoring Stanley. You can encourage him to walk closer to your friend using treats or toys as lures and rewards for moving closer.
Most of all, remain confident and upbeat yourself, but calm and not overly talkative and animated. If you are anxious about Stanley being nervous, he will sense it and think there is danger.
How does he do with other dogs? Is there a doggy friend who might make him feel more relaxed outdoors?