Theresa May has made a (good) speech with which I agree mainly, but not wholly. In any case, it has probably won her the election - if that has not already been won.
To broaden the geopolitical spectrum somewhat, it is surprising that France escaped this wave of terrorism during her Presidentials, given that roughly 10 times more French have died over the last twelve months at the hands of barbaric so-called 'Islamic martyrs' than have Brits - including the horrors perpetrated in Manchester.
If the current modus operandi of Jihadists is anything other than disparate (and I've no idea whether this is the case or not), then one could imagine that a concerted effort by them, on the UK, post Brexit, is not inconceivable, in the way a wolf-pack would separate sheep from the flock. I would assume that the big cheeses at ISIS are as far removed from everyday life as Paul Dacre is at the Daily Mail, so any attempt to destroy the English way of life would seem a reasonably goal given the symbolism of Anglo-saxon culture in the post-modern world. The question is, do we sacrifice all by blindly lashing out (as was the case when we (erroneously) invaded Iraq in 2003, thus largely fueling the current resentment against the 'west'), or do we strive to preserve our democratic ideals at all cost?