There is no connection between leaving the European Union and Sunday’s terror attack in Streatham.  But that is not how it will seem to some voters.  They were told that Brexit means taking back control.  Which they will believe means incarcerating terrorists permanently.  They will not take kindly to being told that this can’t be done because of our membership of the European Convention of Human Rights – and the obligations that flow from it.

Others will be more cynical.  They will remember that it was briefed, after the London Bridge terror assault in November, that Boris Johnson would “lock up terrorists and throw away the key”.  The key was not disposed of in the case of Sudesh Amman.  It was turned in the lock and used to let him out halfway through his term, as the law required in his case.  He then stabbed three people last weekend.

Robert Buckland told the Commons yesterday that emergency legislation will be introduced to minimise the risk of a similar attack. “The underlying principle must be that offenders will no longer be released early automatically and that anyone released before the end of their sentence will be dependent on a risk assessment by the Parole Board,” he said.

Which is all well and good.  But, first, such change won’t prevent terrorists from being released sooner or later.  Second, risk assessments can go wrong.  Finally, future sentences don’t cover present offenders.  Bill Cash raised that last point with the Justice Secretary, demanding that “the legislation will be fully retrospective, notwithstanding article 7 of the European Convention on Human Rights”.  Buckland’s reply was non-commital.

One wonders what he made of the Number Ten source who said yesterday that responsibility for the Streatham attacks lies with “terrible decisions made over past 15 years and the shocking influence of lawyers on policy” [our italics].  On the face of it, this is an astounding claim: after all, Cash himself, for example, is a lawyer.  It is not obvious that this hero of the Eurosceptic movement somehow shares the responsibility for terror attacks.

But Downing Street is getting at the issue that the Stone MP raised yesterday, and that we highlighted at the start of this article.  After Brexit, Dominic Cummings once wrote, “we’ll be coming for the ECHR referendum and we’ll win that by more than 52-48”: he is exactly where those angry voters are on taking back control.  The Conservative Manifesto addressed the issues concerned less vividly: indeed, it didn’t specifically address the ECHR at all.

It did however promise a Constitution, Democracy and Rights Commission to probe the Human Rights Act, administrative law and judicial review.  Many eyes will be on it when the Government forms it and selects a Chairman.  Before then, there will doubtless be a legal tussle about whether Ministers can legislate restrospectively in relation to present terrorist prisoners in the way that Buckland promised yesterday.

That will suit Cummings and company just fine.  As this site wrote after the London Bridge assault, “elected MPs, not ECHR judges, should have the final say – whether the matter in question is votes for prisoners, say, or detention without trial.  Ultimately, the policy aim should be for a British Bill of Rights, which would be written…to strike a better balance, inter alia, between national security and civil liberties”.

It will be said that longer incarceration is unnecessary: that better deradicalisation programmes, stricter monitoring and lie detector tests (according to the Justice Secretary yesterday) can do the trick.  They all have their part to play but none can guarantee public safety.  A final point may be worth making.  The most likely next leader of the Labour Party is not only a lawyer but a former Director of Public Prosecutions – during “the past 15 years”, is he not?