It was the usual assistant head sort of chat; pretty one-sided with the use of lots of words like "responsibility", "consequences" and "concerned". By the time his eyes had finally glazed over, I had reached the importance of the need to be honest, not just with others, but with himself. Sermon concluded, I continued down the corridor, probably looking smug in the manner of the horrifying Eric Slatt on BBC1's Chalk.
At the end of the corridor I bumped into a physical education teacher who enquired into my training schedule. "Fine," I said. "I'm all set for Sunday. " This was a reference to Edinburgh's annual 10-kilometre Caledonian Run.
The swish of the swing doors from the far end signalled Craig's exit from the building, but they also provided a fanfare for my downfall. I knew that "fine" to my colleague meant four or five runs a week. I also knew I'd been out running just four times since August. I was being, as they say, economical with the truth. In fact, I was sliding into my usual autumn habits of lies and deceit.
Every year I perpetuate the myth that I am "a runner". I talk about my annual 10K run as if it were just one of many. I am to be seen in tracksuit tops. I even buy running magazines. And in all of this, I'm fooling no one but myself.
My wife no longer bothers to snigger as I pack my running shoes for our summer holiday. She knows they will stay untouched. My pals at the football exchange wry grins as I spend the first game of the season explaining how this year I'm going to train really hard for the Caledonian. When it gets to the end of September and I admit I've just been out for my first training run, their faces betray no sign of surprise.
For they all know that I have become the most tedious of characters, a cyber runner. In my head I'm just as much of a runner as I was when I ran cross-country at school. In reality, if I run more than a dozen times a year it would be unusual. I like to think of myself as that youthful athlete, even though all the objective evidence, particularly that in the mirror, laughs in my face. But then maybe that explains the extraordinary percentage of Caledonian Run entrants who are 45 and balding, with facial hair.
Shortly after considering all this, I spotted Craig again and had to fight off a strong urge to prostrate myself before him and confess I was as much into self-delusion about my running as he was about his schoolwork. I resisted the temptation, but it was a timely warning that, as teachers, we should be careful to steer clear of becoming the pots that call the kettles black. Recognising pupils' faults in ourselves can be a salutary experience and can only help in the vital business of including humanity in our classroom relationships. It had been a short corridor but an important realisation.
Meantime, I think I'll take out my medal from London's Marathon '82. I'll reflect on past glories and try to forget that I was well beaten by a pantomime horse that didn't even have to break sweat. That kind of realism just hurts too much.