As we write, the motivation of the London Bridge terrorist isn’t confirmed.  But location, method, and the mock suicide vest suggest that the man responsible may have been motivated by radical Islamism.  So does timing.  It is unlikely to be a coincidence that a terror attack took place in the vicinity during an election campaign two years ago.  Cressida Dick seems to agree: it is noticeable that her post-attack statement swipes at “the empty ideology of terror”.

The most plausible explanation is that an appeal has gone out from an extremist group, and that a deranged individual has responded, as such people may always do.  That his instrument was a knife rather than a bomb may demonstrate how the options of Islamist terrorists have dimimished in recent years: a reminder of the work that the police and security services do on our behalf.

None the less, two victims are dead and more injured, and there can be no certainty that the assault will be the last of the campaign, if Dick’s hint and our assumption are correct.  The groups and individuals who plan and mount such attacks don’t usually attempt to swing the contest one way or the other.  Rather, they seek to assert their presence, grab publicity, recruit members and, as it were, “be there on the night”.

Boris Johnson has suspended Conservative campaigning for the evening; Jeremy Corbyn has come out to do the same for Labour.  There is a case for a longer pause after more facts become known but, on balance, the presumption must be that the campaign should carry on.  The more terrorists seek to throw democracy off balance, the more it must strive to stay on its feet, and carry on as usual.

Corbyn to date has followed his 2017 campaign playbook, doubling down if anything on its essentials.  There are more pledges, even bigger headline spending, and relentless attacks on the Conservatives, especially over the NHS.  Labour’s strategists will be remembering their success, last time round, in turning the Tories’ status as the party of law and order against them, as the Labour leader tore into the Conservative record on police funding.

He will be tempted to follow that playbook again after today’s incident, and it is possible that the gambit will work for him if it is taken, enabling Labour to carry on rising in the polls, as we noted this morning that it is doing.  But it is just as likely that, if Corbyn takes this route, it will lead to a cul-de-sac.  For while he is following his own example in 2017, Boris Johnson is not following Theresa May’s.

Her campaign thought big; had no economic message – and no counter-attacking zip either, especially on police budgets, on which she was vulnerable as a former Home Secretary.  Johnson is taking no risks; knows the scene in London, and has deliberately adopted a harder Government profile on law and order, spearheaded by Priti “I want criminals to literally feel terror” Patel.

It may be that his well-established pledge of 20,000 more police officers cuts no ice with voters.  But it is unlikely that Downing Street will simply sit back, if Labour seeks to link terror to a “austerity”, and soak up the punishment.  Corbyn is a known factor now as he was not in 2017, and Team Johnson will counter-attack if necessary, arguing that if one cannot run the economy properly one can’t support the police effectively.  And that terror attacks shouldn’t be politicised.  But what will Number Ten do if, God forbid, more attacks come soon?