The Single Transferable Vote electoral system returns more than one representative in each constituency.  The Additional Member one returns representatives with no constituents at all.

One of the strengths of First Past The Post – though it is shared by the Alternative Vote system, and by the use of two separate rounds of voting – is that it matches one MP to one constituency (at least here in Britain in modern times).

Each MP must therefore represent all his constituents, no matter how they vote.  Which is why some victorious candidates at general elections make a point of taking their rosette off after their victory speech at the count.

The newly-elected MP is no longer a creature of faction – or so the theory goes – but the representative of some 80,000 people or so. And he can’t properly speak for them if he doesn’t mix with them.

And so the scene is set for the debate on MPs’ safety that has followed the ghastly killing of David Amess.  One might think from reading the reports that MPs themselves are divided into two camps – one favouring less direct contact with constituents, and one not.

But our sense is that the discussion among MPs is arch-shaped.  At one end are those who favour fewer face-to-face meetings and more carried out on screens.  At the other are those want to keep calm and carry on.

However, most of the MPs that I’ve spoken to during the past few days are somewhere in between – though on balance nearer the status quo position.  This makes sense.

It would be reactionary, in the literal sense of the word, to insist that nothing must change before assessing proposals for change – such as those that will come out of Priti Patel’s review.

Alarms and CCTV have been recommended as standard practice since the murder of Jo Cox, and MPs are already offered advice on security (such as reinforcing doors and windows) in the wake of specific threats.

It may be that some MPs will want a form of security at their surgeries, say: a topical consideration given the circumstances of Amess’ brutual killing.

And it is just as debatable as was in the 1940s that “the bomber will always get through”, since it would be odd to assert sweepingly that no new measures could ever make a difference.

Nonetheless, most MPs are level-headed enough to recognise that there is a limit to what can be done.  For example (and sticking for a moment to surgery arrangements) if a constituent has only just moved into a new property, he may have no evidence of his address.

Searching for weapons could simply transfer the risk to MPs’ staff – who after all are often more exposed to abuse and threats, especially over the office phone, than their employers.  Caseworkers, reseachers and secretaries are the unsung heroes of constituency work.

Some MPs like holding their surgeries in different places, as Amess did.  This offers the opportunity to get out and about.  For those with big constituencies, or seats centred on several towns, this is hard to avoid  – and desirable in principle.

Is it seriously proposed that they should all hunker down for surgeries in one central security-enhanced building?  As for Zoom and the like, what about those who don’t use the internet?

Different sources give different figures, but there’s no doubt that the percentage rises among older people.  Some doctors haven’t returned to face to face surgeries, and there is a row about them not doing so.  Should MPs really get themselves in a similar position?

Then there is MPs’ life in the constituency outside surgeries.  Admittedly, some live a long way away from their patch.  Or aren’t based there most of the time, since they have a second home.  But it is less common than it was to be an absentee landlord.

No wonder: more people vote on the basis of choice rather than of class – they shop around.  The result is that more MPs do what others would do anyway: their families live and shop locally; their children are at local schools; they are members of local clubs and charities.

They are stopped on the street.  Sometimes a few pleasantries are passed.  Sometimes a few unpleasantries.  People raise local gossip, comment on the latest whatever-it-is at Westminster or on social media, or treat the encounter as an informal surgery.

This returns us to where we started.  It is simply impossible under our system to screen MPs off from their voters, like the man in the cartoon who is magically insulated from the weather as he walks.  Not to mention undesirable.

In one sense, we shouldn’t want uniformity.  Each MP must ultimately make his own decision about how to live.  In another, we should get a bit more.  Police responses to MPs reporting threats or abuse seem to be very variable.

See this interview with Paula Sherrif, who says that police took weeks to view CCTV footage of swastikas left at her office, told a man who harrassed her repeatedly that they sympathised with him, and laughed when she reported a death threat.

Or read Andrew Rosindell’s account of how he repeatedly reported incidents to the police but “quite often they literally don’t do anything, or the onus is on me to give endless statements which lead nowhere.”

Police officers at constituency surgeries each week wouldn’t be a sensible use of resources.  And might discourage some constituents from coming forward.  But a more consistent approach to dealing with reports from MPs is overdue.

Should it make a difference to MPs if the killing of Amess turns out, like that of Jo Cox, to be politically motivated – rather than, say, the action of a troll with a personal grievance inflamed by social media?  Is the outrage over Twitter overdone?

I don’t think so.  As Bim Afolami writes on this site today, “I know well over a dozen who have had stalkers, or else attackers who have been sent to jail.”  It’s worth reading Nadine Dorries’ piece on this site from two years ago on the subject.

Which isn’t to say that new duties should be loaded on to the Online Harms Bill.  There is a balance to be struck between protecting the vulnerable and freedom of speech.

The least bad solution seems to be opening up social media to legal action, since it is evidently more like a publication than a platform.  Ponder, for example, YouTube’s original ban on a speech by David Davis opposing Covid passports.

David Amess enjoyed being an MP and meeting his constituents.  It’s right to look, in the wake of his killing, for lessons to be learned.  But it would be a terrible irony were the work that he loved doing now to be made more difficult.