The word “nutter” is never far from my mind. I used it last June in this piece (“Please don’t tell me the names of the murderers”); more about that later. I have been meaning to draft a Word of the Week piece about it for a while.

Before last week’s events here in London my most frequent day-to-day use of the word has been when crossing the road with one or both of my children, or when we’re in the car. “It’s a one-way street,” I might say as we cross the road, “But look both ways, in case there’s some nutter driving the wrong way”. Or when some other driver overtakes at a zebra crossing or parks on a zig-zag line I might shake my head and say “Nutter”, rather than the foul-mouthed alternative I’d use when driving alone. On Saturday evening my son and I went to the Shepherds Bush Empire, trying to get tickets for next week’s live performance of “Ziggy Stardust”, which will feature Tony Visconti and the remaining Spider from Mars, Woody Woodmansey. It’s sold out, although when the same artists performed “The man who sold the world” in 2015 we were able to get tickets on the door. As we were walking back to the car down that one-way street behind the theatre someone was driving the wrong way down the length of the street. “Nutter,” I muttered, pretty much involuntarily.

In my mind the word “nutter” describes someone based on their behaviour; it doesn’t necessarily imply mental health problems. It indicates that someone has done (or is doing) something on the line that runs from “a bit daft” to psychotic and deranged.

If one of your friends does or says something daft you can call them a nutter and be confident that they won’t think you’re questioning their mental health. Related terms “nut” and “nut-job” are different. Americans use the word “nut” to describe enthusiasts, saying “sports nut” or “film nut” in the way that we would say “sports fan” or “film buff”, so it’s usually an inoffensive word. It’s not used so much in the UK. “Nut-job”, in my view, is not affectionate; it implies mental instability, not just questionable behaviour, and I never use it.

As with so many other words and phrases an example comes to mind from a pop song. “Down in the tube station at midnight” by the Jam features the words “The last thing I saw as I lay there on the floor was / Was ‘Jesus Saves’ painted by an atheist nutter / And a British Rail poster read ‘Have an Away Day / A cheap holiday, do it today’”. When I was younger I also believed that the word occurred in the Jam’s follow-up single, “Strange Town”. The second verse includes this: “You can’t be weird in a strange town / You’ll be betrayed by your accent and manners / You got to wear the right clothes / Be careful not to pick or scratch your nose”. I misheard that last line for years as, “Be careful, nutter people smash your nose”.

Returning to my piece from last year mentioned in the opening paragraph, I used the word nutter back then to describe the mass murderers who, between them, killed over a hundred people in Orlando last year and in Norway in 2011. I’ll use it now to describe the man who killed four people in Westminster last Wednesday: he was just a nutter.

I’m not the only one. Kay Burley, reporting live on Sky News, described the attacker as “some … nutter”. This was included in an item on Jeremy Vine’s lunch-time show on Radio 2 last Friday which discussed the use of the word. You can hear it, for the next 27 days, here. At 20’30” he asks the following: “Couldn’t we describe him as something else, more ordinary?” [At this point I shouted at the radio, “Yes, he was a nutter”.] Jeremy Vine continued: “We could talk about him being deranged, a lunatic … a nutter someone said.” I knew that he hadn’t heard me, but felt a little bit spooked by this. I hadn’t heard the Kay Burley clip by this point. As I wrote last year, forget the names of the killers and remember the names of those who died. Rest in peace Keith Palmer, Kurt Cochran, Leslie Rhodes and Aysha Frade, murdered by some nutter in the city that I am proud to call home.