Ten minutes later I arrived at the staffroom door to find it locked. Two senior managers were inside.
"Colin's been suspended. They're taking his computer," said a colleague standing outside. "I warned him about fooling around with his female students," said another.
The managers were checking Colin's email for incriminating messages and to see how he had graded his loved one.
We have had a lot of staff disciplinary problems at college lately. When I started teaching in the late Seventies such events were rare.
I remember a mad drama teacher sacked for devising an obscene nativity play. After that, we waited almost a decade before another colleague hit the rocks, this time a French teacher charged with misappropriating funds from an exchange visit to Marseilles. With friends in high places, he was cleared and is now head of modern languages. Few remember his days as an international embezzler. I plan to remind him only in emergency.
But there was no such reprieve for Colin. He never returned to college and resigned three months later. The object of his affections, by the way, was his 26-year-old girlfriend Rose. They had lived together for two years.
Affairs between staff and students are not uncommon in colleges of further and higher education. How could it be otherwise, with adult men and women working in such close proximity? Single people take pleasure in each other's company and before you can say "gross professional misconduct" teacher and student are lighting post-coital cigarettes in bedsits off the high street.
But what rankles is that colleges can't even achieve consistency in dealing with people who have relationships with students: some get sacked, others get away with it.
Take Colin's workmate Joe. Eighteen months ago a group of us attended Joe's wedding, and he and his wife Clare have had a baby boy. But up to the summer before the wedding Clare was his student. The difference between Joe and Colin were that Joe was discreet and none of Clare's classmates complained, whereas Colin flaunted his relationship and one of Rose's classmates accused Colin of unfair treatment. I don't know if confiscating Colin's computer proved anything, but I doubt if anyone checked Joe's at all.
A few years ago my head of section accused me of having an affair with a student. It was groundless and my head of faculty made sure all charges were quashed. Nonetheless a few months later my section leader demoted me from heading a higher education programme to a much less prestigious course. I was replaced by his wife.
So why do we have so many more staff disciplinary actions compared with 10 years ago? At the risk of being dismissed as a male chauvinist pig, I think it is partly because we now have far more female managers.
In my own faculty we have a female director and three female section heads.
Administratively, they are superb. But in terms of man management - with an emphasis on the man - they are ruthless.
In the old days a teacher suspected of dallying with female students was given a severe reprimand by his male boss. If he reformed, his career progressed without obstacle. If he didn't, he was despatched unceremoniously.
Female managers, on the other hand, tend to suspend while considering their options. If the offending teacher is innocent or a particular favourite, he will be re-instated. But if he is considered guilty, lacks influential friends or is just someone the head of faculty dislikes, a watertight case will be mounted against him and he will be out.
And counter-charges against managers will have no effect - hell hath no fury like a head of faculty accused of bullying.
Harry Marsden is not the author's real name. The names of people mentioned in this article have also been changed.