With education fast becoming a competitive marketplace, headteachers - many already facing recruitment and retention difficulties - are under more pressure to offer a wide range of courses for pupils. This may be good news for the learners, but not necessarily for secondary teachers, who are increasingly required to teach subjects they are not trained for. Finding the cash for additional training and resources is a tall order for most schools, which means teachers can feel out of their depth.
Jill Harris teaches English at a large secondary school in Devon. In her previous job, she was asked to introduce a new GCSE in expressive arts, which, she describes as a "terrifying" experience. "I'm trained in English and drama, so it was assumed that this was near enough to expressive arts," she explains. "I thought 'Well, I have an interest in expressive arts, so that should help.' There was no training. Nevertheless, I felt under pressure to get high grades."
While she received informal support from the head of drama, Jill received no formal training and - despite having no knowledge of the subject - was expected to write her own schemes of work.
"I was in the dark most of the time," she admits. "I had no budget for resources and had to beg, steal and borrow things from all over the place."
"I had 26 boys. We did Romeo and Juliet in a gangster style. They researched gangsta' culture from documentaries on modern gangs in Chicago and New York. We looked at graffiti art and painted a mural in school. We researched the music they loved and wrote lyrics in that style. They certainly enjoyed themselves."
She may have captured the imagination of pupils at her tough inner- city boys' school, but Jill would not be keen to repeat the experience. "I did enjoy it in a way, but I wouldn't do it again unless I had training and a lot of support. I'm a head of department and always support non-specialists with schemes of work and help with planning and marking. I think that's only reasonable.
"The biggest thing I learnt was to say No. Just because I can teach English doesn't mean I can teach everything!"
Lee Forbes can sympathise. Half this Southampton teacher's timetable is taken up with music lessons, even though he trained for history.
"I'm pretty sure I got this job because I used to be a session musician," he says. "Since the head of music retired, I've been teaching a big chunk of the key stage 3 classes. I wouldn't mind, but I haven't even got an A-level in music and sometimes wonder if the kids are getting a raw deal."
According to Carol Skewes, head of the Cornelius Vermuyden school and arts college in Canvey Island, Essex, recruitment and retention - particularly in shortage subjects - have a big part to play. She says: "As part of our selection process, we ask staff to teach a lesson in their specialist subject, which helps us form an opinion on their teaching ability and ability to enable students to learn.
"Problems can arise in subjects like maths and other subjects where there are shortages. In the past couple of years in the South East, it's become more difficult to recruit maths and science staff, and government initiatives can have an impact. Recently, I've found it difficult to recruit PE staff, as many have been attracted by the newly designated sports colleges which are able to offer better sporting facilities.
"So in order to fill posts, we do have to consider second subjects, but, first and foremost, we're looking at how effective teachers are at teaching."
She admits that if the practice of using non-specialists becomes too widespread in a school, it can be problematic. Specialist teachers bring expertise, engagement and may offer a greater degree of challenge to their students. But some teachers are "inspired communicators" who offer all of this and more.
As Ms Skewes points out: "We only need to look at primary teachers to see how multi-skilled and talented some teachers can be."
She believes non-specialists can actually bring benefits to other subjects: new perspectives on assessment, target-setting, planning and approaches to teaching and learning. It can also give teachers the chance to broaden their skill set and even change career path, without changing schools.
Teaching her non-specialist subject has given Jo Jackson the chance to become a head of department after three years. "I initially trained to teach history, but at interview, the head asked if I'd teach key stage 3 RE as well," says Jo, who works at the Willink school in Reading, Berkshire.
"I didn't see it as a problem. Even in history, I have to teach things I haven't studied before, so I thought 'Why not?' At first it was just key stage 3, then in my second year I starting teaching GCSE. The head of department was really supportive and gave me schemes of work to follow.
"When I was offered the role as head of RE, I had to think carefully as I didn't want to give up my history completely, but it was such a good career opportunity. I don't want to give up my history completely, but I'd quite like to expand the RE, maybe introduce philosophy and ethics at AS level.
I'm really pleased I took on the RE. If I hadn't, I might have had to move to another school for promotion."
Chris Keates, general secretary of the NASUWT union, acknowledges many schools are under pressure to recruit and retain teachers, particularly for specialist shortages, but thinks teachers often lack access to appropriate support and training. "Teachers are committed and conscientious and want to do the best for their pupils." he says. "Those who find themselves teaching outside their specialism face added pressure over and above those experience by teachers generally. They feel particularly vulnerable during Ofsted inspections as this system makes no allowance for their situation."