Listening to the news it has felt to me as though the Remain camp have been trying to exploit this deranged person’s horrible act and try to tar all Leave supporters with the same brush.

That won’t do either.

Down that path we get to that horrible quote from HHGTTG “I’m going to kill my brother and then kill you on the grounds that your brother did it.”

Killing people is fundamentally wrong and you can not advance any logical argument in any direction from an unsound foundation.