Lab still nipping at 11 months

[reikizen]

My bloody lab is still nipping at 11 months! The problem is she doesn't do it at home so I can't correct her. She does it on walks when too far away from me to stop her (randomly, she will be fine for weeks then today she nipped someone's fingers). She is a very, very excitable dog but has improved with one to one training sessions.
What the bloody hell can I do? We are going to get in serious trouble soon is a muzzle a solution?

You don't have a nipping problem, you have a recall problem. Get her on a long line and harness and work on her recall.

Do you think so? It is very difficult to give her enough exercise using the long line as there is really only one place I can take her with it. Would you aim to stop her from socialising with any other dogs then until I have cracked the recall? I don' know any dogs with 100% recall so what am I aiming for would you say? She will also nip if a stranger goes to stroke her occasionally if she is I the lead so do you have any suggestions for that?(hopeful emoticon) I am currently doing training for good manners when meeting people using the clicker and treats so am fairly optimistic.