By Emma Revell Both Labour and the Conservatives have already drawn in firm dividing lines over what this election will be about, but it is security that unites both campaigns, writes Emma Revell Well, there we have it. After months of speculation, the Prime Minister bit the bullet and announced he would be sending the nation to the polls on 4 July. There’s been a lot of discussion in the days since about whether he made the right decision. But at this point, it doesn’t matter. What’s much more interesting than whether Rishi Sunak was right to call the election is what the election will actual…