One of the things that is sometimes misunderstood is why groups, and even message boards such as this one, try to verify the claims someone might make to being a member of a specific Tradition. Some feel this elitist or that we are picking on people. Some feel we should just take them at their word. The problem is that people are not always truthful in their claims. And the bigger problem is that their lies can then lead to other individuals being hurt when they are led astray.
That is why British Traditional Wiccan covens use a process called "vetting" where they ask for someone claiming to have been initiated into a BTW coven to provide proof of their claims. The individual then gets someone who knows them to provide proof of their statement (the vouch).
Before I was BTW my own Trad used this process. Basically what happens is that a person asks to join a group and claims that they have training and/or a Degree from another group. Sometimes this is true, sometimes it isn't. And when you are talking about different Trads there is often a large difference in the requirements for initiation from group to group. So when someone made a claim such as this I always asked them for the name of their prior group leaders or teachers so I could contact them and confirm what they were telling me.
For Gardnerians and other BTW's this becomes even more important because of the oath-bound nature of much of their material. So it is vital to be sure that the person asking to join a BTW coven has the initiation and lineage they claim inorder to keep oath-bound material from being given to someone not properly initiated. That being the case, both the Gardnerians and the Alexandrians have good records of their Initiates and their lineages so that someone can be checked (vetted) and have someone in their upline verify their claims (give them avouch).
So if you are looking to join a group and you are asked to provide the names of someone who could vouch for your claims to training and initiation don't beupset or feel as though someone is calling you a liar. This is a time-honored way of protecting the safety and welfare of the group. If you've been honest with the group beforehand there should be no problem in getting the vouch you need.
Anyone who is legit about their claims will have no problem in responding to such a request. Someone who gets in a huff and says that no one has the right to ask...well let's just say that it is unlikely they are what they claim.