I guessed he'd been invited to his head of department's Christmas bash. It was after last year's bash that all the conversations about dual standards of behaviour for people in public life fell into place. Not only did the said head of department display the reason she's called "Melons", but she allowed them to be photographed before taking the Australian supply teacher away (allegedly) for some "biology practical".
Added to that was the sight of two heads of local schools sharing a spliff and several people having difficulty finding their cars before weaving off in the early hours.
How many, Jeff and I wondered, would be proclaiming in school during the next term that young people should abstain from all the vices being practised that evening?
But Jeff told me he wasn't going to any parties this year. In fact, he was finding it difficult to join in the merriment at all.
This summer, both Jeff's parents died. He's had a hard time of things. The suddenness of their respective deaths. The paperwork. Sorting out their effects. Disposing of property and the house. Coming to terms with being the eldest survivor of his part of the family tree.
Many are the evenings I have had to console him and encourage him to think about his wife and children - and all the other children who rely on him.
But here's the dilemma.The kids in school expect Jeff to be his "usual" daft self. Cracking jokes. Taking the Mickey. Smiling. Chatting. Coping with the mayhem around him. Kids expect this and find it hard to cope with a sullen, snappy, unapproachable Jeff.
Kids - at school or at home - expect consistency. The teacher who laughs at an event today and punishes for that same event tomorrow is difficult to respond to. Kids try to respond to what they know. They acknowledge that Mr So-and-so never smiles and work with it. The maths teacher demands silence. French always has an accepted undercurrent of conversation.
Kids will also respond if they know there's a change in the rules. After last year's bash, staff with a hangover might have asked for consideration from their students - a bit of hush, only easy questions.
But Jeff wasn't sure what to say - or, indeed, if he wanted to say anything about his parents. Even if he had, who, among the students, would understand that, six months on, Jeff is still struggling to cope?
We are like robots to many of the kids that we work with.We appear, dispense knowledge and advice, then we (and they) shuffle off to the next lesson. We don't have time to talk about music, films, football results, the weekly trip to the supermarket, having the flu.
Perhaps if we did, we would be more willing to accept the reasons why a member of 9Z is not as enthusiastic about work as usual today - and they would understand why Jeff doesn't want to celebrate Christmas.
The writer, who wishes to remain anonymous, works with excluded pupils in East Anglia