She had a place on the senior management team and her eye on the next move, to deputy headship. Then she became pregnant with her first child.
Susan had originally planned to return to work at the end of her maternity leave, but her school was unwilling to consider the prospect of a job share. So she quit. Five years and another child later, Susan, 34, has gone back to the classroom, but this time as a supply teacher, working two or three days.
"It is working out perfectly. There are a couple of schools that are using me regularly, and I enjoy it," she says.
Susan says it was only after she left her full-time job that she started to feel she was getting her life back. "Before, nearly everything I did revolved around the classroom, and there was all the work I had to bring home. I was totally ambitious and wanted to do as well as I possibly could," she says.
"Now I have more time and energy, I can go to the gym rather than flake out in front of the TV, and I've got a bit of a social life."
She admits there are downsides. There were the early morning telephone calls when she first started supply, and she misses the social side of being a regular teacher. She also has to follow somebody else's work plans and get everything done in one day, although this also means there is no marking to take home.
Susan hasn't ruled out going back to full-time teaching, or even resuming her climb up the career ladder, but she doesn't regret her decision to take a step back. "At the moment this suits my lifestyle, and once you have got a family, that is your first priority," she says. "And I'm happy teaching rather than being snowed under with paperwork."
Philip was deputy head of a primary school in the North West. He has almost 30 years' teaching experience, the National Professional Qualification for Headship and had applied for headships.
But a full teaching timetable on top of his leadership role and administrative duties gradually became too much.
"I was getting up at 4am to do paperwork, and remember one time sitting in my caravan on holiday in Austria writing maths documents. I just cracked up," he says. Philip was signed off sick for stress and depression, but found his school unsympathetic. He resigned and last autumn started supply teaching. Although his confidence had been knocked by his previous experience, he is now working virtually full-time.
"I enjoy my life now," says Philip, 53. "The downside is there is no guarantee of work, and I miss the personal relationships with the staff and the pupils, but I have got my life back. Before, I was working early in the morning, late in the evening and every weekend.
"The reason I went into the job was to work with children. Now, I do that as conscientiously as I can and I'm home by 4.30pm."
Nick Morrison* Some names have been changed