Teachers have never had the raunchiest image, but when two from Northampton were caught having sex in a college gym last month, by students who filmed their “liaison” on camera phones, the public was left speculating as to whether there was more to teachers than meets the eye.

The profession was wondering: “Where did they find the energy?”

“When I was teaching in the UK, I fell into the ‘What is sex?’ group,” says Jill Ungless, who now teaches high school English in the United States. “I vaguely remember something that involved Rock Hudson and Doris Day in single beds, kissing passionately with closed mouths.

“There was no time in my life for going out and meeting men, or rather, I couldn’t say ‘No’ to anything my head asked me to do, so I ended up working weekends, evenings and holidays. I was 23. And that was supposed to be my sexual heyday!”

Jill is not alone. A recent survey carried out by the Teacher Support Network found 74 per cent of teachers felt their job had a negative impact on their love life. And it’s not just singles missing out. Long hours and heavy workloads mean many teachers feel they neglect their relationships.

“During term time, I hardly see my husband,” says Julia Davenport, a primary teacher from Merseyside. “I rarely get home before six. Then it’s a quick TV dinner followed by three hours of work. After that, all I want is bath and bed. Try finding the energy for sex after a day like that!”

Relationship psychologist Susan Quilliam is not surprised. “Teachers are putting themselves on the line each day,” she says. “They are pouring so much physical and emotional energy into their job, it’s little wonder loved ones often feel short changed.

“Anyone who is feeling stressed at work is going to be on a short fuse, less likely to want to communicate with their partner and have less of themselves to give. And if one or both partners is feeling stressed, recreational sex is often one of the first things to go. All this can take its toll on even the most solid relationship.”

When one partner is not a teacher, the relationship can also suffer from what Ms Quilliam refers to as the Get-a-life syndrome, when, much to the irritation of their partner, the teacher lives and breathes school. “The teacher may feel frustrated because they feel their partner doesn’t understand the stress they are under,” she says. “By the same token, their partner may feel frustrated because all they can talk about is school.”

Engineer Mark Quinn can empathise. He has been dating Lucy, an English teacher from Lancashire, for three years. “Sometimes I think to myself, ‘If I hear one more thing about that poxy school I’m going to explode’. Don’t get me wrong, I think it’s great that Lucy is so passionate about her job, but if she’s not planning or marking, she’s talking or thinking about school.

“I dread nights out with her colleagues. I’m not the slightest bit interested in Matthew’s dyslexia or Sophie’s behaviour problems, but while I’m trying to have a relaxing Friday night down the pub, they’re all banging on about school. I don’t feel the need to talk about my job all the time. Why do they? I also get frustrated with the demands Lucy is under.

She’s always being asked to stay after school for different things. Her headteacher gets every last drop of energy out of her and, during term time, there’s little left for me. Sex? You must be joking. That’s a holiday treat!”

Is the solution, then, for teachers to date other teachers, who are more likely to understand the stress they are under? According to the Teacher Support Network survey, 92 per cent of single men and 85 per cent of women are willing to give it a go. But as Mark Christie found out, staffroom romances have their own drawbacks. “I had a stupid fling with another teacher,” says the PE teacher from Birmingham. “She was married; I was engaged.

“I wasn’t proud of myself, but the reaction from the rest of the staff was awful. People would whisper about us every time we walked in the staffroom.

I already felt like the biggest bastard on the planet - I didn’t need their disapproval. Since then, I’ve avoided dating colleagues. ” Jo Bird is also wary - for different reasons. “I started seeing Jon when I was a student teacher, training at the school where he was head of department,” says the London history teacher. “At first, it was great. We got on really well and had so much in common.

“But after a while, I started to realise how boring it was to date another teacher. John was a real workaholic and all he seemed to want to talk about was school. Listening to him banging on about target-setting and schemes of work all the time was a huge turn off. Plus we were both so tired that sex soon slipped off the agenda. It wasn’t long before he got the push, which was very awkward, as I had to see him every day.”

But teaching doesn’t have to spell disaster for relationships, insists Ms Quilliam. The key to keeping romance alive is creating and maintaining boundaries. “It’s a good idea to agree a cut-off point, a time in the evening where you’ll stop working or talking about school issues,”’ she says.

“The nice thing is that you get the same holidays to spend quality time together. It is also vital to put aside time at weekends to spend time together. And if finding time for sex is the problem, it often helps almost to ‘book time’ together. If you both agree you are going to spend time together on a Saturday night, for example, you are more likely to feel relaxed enough for intimacy.”

Patrick Nash, chief executive of the Teacher Support Network, points out that those experiencing difficulties shouldn’t be afraid to seek help at work or outside.

“Achieving work-life balance and rebuilding relationships takes discipline,” he says. “A weekend away without the children, if you have them, is an immediate priority, followed by a private conversation with a senior colleague to consider ways to reduce your workload or enable you to make time to meet deadlines. ” *Names changed to protect the guilty. Too tired for sex, page 3, TES