Re: A false argument
"It's pretty clear that for most people wanting to leave, immigration is the key factor."
Not sure that's true. Immigration is one of the most talked about, because its the current example of the EUs inability to come to a decision about anything. A year or two ago, the big issue would have been the economic collapse of the euro zone.
Anyhow, the main issue for me is sovereignty and not wanting any part of a european super state.