London

I'm in a room tonight with blue lights flashing past outside the window. It's London, and I'm used to a certain amount of first responders going about their business.

Tonight it's different. It's once more because of another murderous terrorist incident in London.

As one of many, I've walked past the bustling area where it unfolded around five times in the last few days.

Like most Londoners, I'm used to the heightened state of awareness. The messages on public transport, "See it, Say it, Sorted," and the frequent and sudden disappearance of rubbish bins from train stations. That shared look on the Piccadilly line for the silly tourist that has left their airport luggage unattended. Bomb alert prompt scripts in the workplace.

When the last knife attacks occurred around Borough Market in 2016, I could scarcely believe it. Then we had the truck driven down the pavement on Westminster Bridge. I realise I'm getting used to it again, like when we used to get evacuated with IRA bomb scares.

Like many others, I've watched with casual interest as new safety bollards are added, and smiled that some streets get special flashy protective bollards styled like the ornate masonry such as along Parliament Street and Whitehall.

I'm used to seeing flatbed trucks carrying portable barricades around and dropping them onto a pinch point. There was plenty of that type of action for the Olympics in 2012.

And as I crossed over the road by St Paul's Cathedral the other day, I cast an eye along the road to one of the old blue Ring of Steel control points left in the road but unmanned since the end of IRA bombings.

It's almost impossible to predict this cowardly terrorism, but fortunately proud London's spirit is uncowed.