The Police are treating any issues like that as a hate crime and are investigating (the case of the letters in peoples doors is one that they are looking into there are others). The Scottish ref, also had a similar thing going on. The people wanting to leave and those wanting to remain had so many people on either side flinging shit at each other. A lot of problems were causing during that campaign.
Sadly both the remain campaigns in the Scottish ref and the UK ref had a fear based campaign. Which in my eyes only serves to alienate the voters more.
Is it me or is May whos going for PM looking like Thatcher 2.0