I came out of my year group assembly to be greeted by my head, who said: "Mr Wilson is here to see you about Justin."
Justin had been absent more times than present that year, so I felt I knew what this would be about. But as I walked up to Mr Wilson, the head whispered in my ear: "By the way, he's armed."
Trying not to look anxious I strode off with Mr Wilson in tow, taking in his bull neck and rather protruding eyes. In my office, I tried to remember some amateur psychology - I shook Mr Wilson's hand and touched his right arm with my left hand as I did so. I had some vague recollection that this was a salesman's technique to make the other person feel warmer towards them. It was worth trying.
I invited Mr Johnson to sit down, and as he did I said: "I understand that you are armed and that is making me feel very uncomfortable. Would you please take your weapon out and put it on the coffee table."
Much to my surprise, Mr Wilson proceeded to remove a kitchen knife from where it had been concealed up his sleeve. The blade must have been a good five inches long, but I feigned nonchalance.
"Thank you," I said and then turned the conversation to Justin.
Surprisingly, the rest of the 30-minute meeting passed uneventfully. Justin claimed he was being bullied and Mr Wilson was in to "sort out" those who were allegedly attacking his son. I managed to persuade him that threatening pupils with a knife was not likely to result in a good outcome.
During the next morning briefing, the headteacher rather cryptically said: "You have to admire the coolness with which a head of year takes a parent away for a meeting, knowing that the parent is armed." Everyone, apart from me, looked baffled. I think it was a compliment.
The writer is a secondary teacher from Gloucestershire.
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