Sir David Amess stabbing: Tragic reminder of growing risks faced by MPs

"It could happen to any one of us."

Those were Sir David Amess's own words, describing the danger that MPs can face, and the awareness they all carry, that their work can - in rare and terrible circumstances - put them in harm's way.

In his published diaries of a long life as an MP, Sir David wrote of the creeping risks: checking the locks, taking care not to meet people alone, alert to what could go wrong.

The contract between us and our politicians is not written down anywhere. Yet part of it is understood by everyone.

We expect the MPs we elect to see us in person, not to hide behind Parliament's ornate gates and wood-panelled walls.

That demand is met gladly by the vast majority of MPs.

But, increasingly, the job has been accompanied by abuse, intimidation - and risk for MPs and their staff.

One member of the cabinet told me today: "Everyone has had a threat... everyone has had frightening moments."

Dealing with harassment, coping with security concerns and reporting those concerns to the police, is sadly routine in politics in the 21st Century.

It is inevitable in the coming days that there will be calls for a kinder atmosphere at Westminster, and cooler heads in real life, and online.

It is not, however, inevitable that anything at all will change.

With an agonising echo of the murder of Jo Cox, another life has been lost today. Another family has lost a parent and partner.

Another MP killed doing the most important part of the their job - spending time with those he represented, and listening to those he served.