the British are not generally so xenophobic, as you will well know,
You're joking right ?
The Brexit campaign is largely based around xenophobia i.e. leaving the EU would supposedly allow the UK to control it's own borders which would mean less migrants coming to the UK. Many people in the UK who are sympathetic to leaving the EU are dumb enough to believe that leaving the EU will result in the Poles, Romanians, Hungarians etc leaving the UK.
I find myself increasingly frustrated with the fact that we have been presented with a referendum but no politician can give the people a clear idea as to the consequences of either decision-they simply DO NOT KNOW. Instead we have the British public having to decide how to vote based on rhetoric coming from both sides of the argument.
There should be other factors to consider such as the economic impact and the broader argument of sovereignty but these factors would be difficult enough for the common man to understand even if they were clearly explained to us.
One topic that will grow and grow over the coming years is Turkey's application to join the EU and many people are favouring a Brexit as a result.