Dave, I personally find it more convincing if someone relates a direct experience than (say) points to a newspaper story – I know the papers don't always tell the whole truth!
You may choose not to believe what someone says, for whatever reason. You may even say, "I find that very hard to believe", which is a (barely) polite way of saying "You lie". I do not know Alison, but at the moment I have no reason to doubt what she says. I can certainly believe someone being under suspicion for having a particular accent: I have first-hand experience of seeing someone arrested (and charged, but found not guilty) for less. I will not elaborate further as I have no documentary evidence.

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