As a supply teacher Rebecca Morgan would turn up for work like a latter-day Mary Poppins. Crisp and fresh in pinstripes and stilettos, with a bag full of tricks for any eventuality, she was never short of work.

Raised in the Yorkshire Dales, she was in great demand on her home patch.

Musical, resourceful and full of fun, she is the sort of teacher who might sing her way through the daily register of children’s names. She wouldn’t dream of turning up to work without a wall stapler and fishing twine to hang children’s artwork, her flute or her favourite story books.

Now she’s running a supply agency from the Dales, and expects the same commitment from the teachers on her books. It’s a thriving family business, which began life on the kitchen table at her home in Grinton on the banks of the River Swale; it now has an annual turnover of pound;500,000.

The company’s success, says Mrs Morgan, is down to careful selection of teachers - half are turned away - and the application of stringent standards to their work. It is a service which aims to match teachers to schools and not to rip anyone off. “We aim to make a living not a killing,”

she says.

Rebecca Morgan’s father was head of Gunnerside, a small primary school in Swaledale with fewer than two dozen pupils. She was educated at Gunnerside and a local secondary, then worked for a bank before, as a mother of three, becoming a teacher. Unable to find permanent work as a primary NQT in North Yorkshire and not wanting to move away from the area, she went on supply.

It proved a lonely existence. She felt she was unaccountable, often ill-briefed, and with no idea of what she was walking into most of the time. “Schools just had a list of names. There was no real communication. I would be told that I was to take Year 6, and find a reception class waiting for me. I would be told that there were plans for me to follow, and find the teacher’s desk bare.”

She had to rely on her own self-discipline, turning up early with a bag of resources prepared for whatever lay ahead and leaving the classroom tidy at the end of the day with a report for the teacher. She liked to be well dressed, pencil-skirted and bejewelled, even if she was to be spending half her day on her knees in the sand pit. Schools liked her. They liked her smartness, her professionalism, her approach with children, and the work flowed in; more than she could take on.

After turning work down for a couple of years, Rebecca Morgan decided to act. Local schools were clearly desperate for high quality supply teachers who were able to cope with the demands of rural areas, such as mixed-age classes, with sometimes a whole key stage in one sitting. After consulting local headteachers, deputies and fellow supply staff, she decided to set up an agency.

With the help of a pound;1,000 grant from the Prince’s Trust, she set up an office. “One of the chaps working for the Prince’s Trust was a governor of a school over in Pateley Bridge and he was interested in the project,”

she says. ” The trust believed we had a unique selling point.”

That was six years ago. At first she ran the agency alongside her own teaching with a turnover of little more than pound;26,000. Now she’s managing director of Principal Teachers, still run from her home in Grinton.

There are 120 teachers on the books, two-thirds of them women with young children; people such as Patricia Bloomfield, 31, a full-time Year 6 teacher for nine years, who joined Principal Teachers after having a baby.

She aims to supply teach while she raises a family, enabling her to continue her professional development, while giving time to her own children.

“I can enjoy classroom practice without all the additional responsibility of planning and co-ordinating,” says Ms Bloomfield. “At Principal Teachers I feel like part of a big family unit; they are interested in how you are getting on, they keep an eye on you and give you choices.”

Every morning, Rebecca Morgan and husband Steve, a former electrician and now Principal Teachers’ accounts manager, wave their three own children - Emily, 11, Mary, 7, and five-year-old Kate - off on the school bus, then get down to work. Lorraine Hall, Mrs Morgan’s stepmother, works as principal recruitment consultant, while Mrs Morgan’s father, the ex-headteacher, is on hand to give advice.

All teachers are recruited on the basis of face-to-face interviews. Mrs Morgan says she is looking for staff who are calm and positive with children, who can think on their feet and are flexible. They must supply two references and are subject to enhanced Criminal Record Bureau checks.

“Good supply staff are like gold dust,” she says.

Schools are charged a day-to-day commission but no introductory or registration fee. Rates are standard for the profession, with experienced teachers earning nearly pound;140 a day at the top end. Teachers are required to dress smartly, turn up half an hour before the start of school, and to stay until all children in their class have left the premises or been met by parents. They will then finish off any marking and report on the lesson to the full-time teacher. The agency always contacts the school to make sure the day has gone well and also provides forms to its teachers to give feedback on the school.

Principal Teachers is waiting to be awarded the quality mark, introduced by the Department for Education and Skills several years ago to set minimum standards for agencies in the way they recruit, interview and manage staff and how they work with schools and teachers. Mrs Morgan believes the quality mark should be a statutory requirement for supply agencies.

There’s a party every year in a local pub for school staff and supply teachers to meet and mix informally. Mrs Morgan has published a book of local children’s poems. Supply teachers are sent birthday cards, Easter eggs, Christmas gifts. And, according to schools, there’s someone available to talk in the Principal Teachers office seven days a week.

“They supply excellent teachers and always try to match what we need,” says Carol Thompson, school secretary at Romanby primary in Northallerton, North Yorkshire. “They are good people to work with, they work as a team with us and can always be contacted.”

Steve Roberts is an ex-rural headteacher who’s abandoned the burden of admin and returned to the classroom on supply, a job he thoroughly enjoys.

Working with Principal Teachers, he says, has made the job doubly enjoyable. “I do a good job and they make me feel appreciated. I always get feedback and we are on first-name terms. It’s a very personal approach.”

In demand

* Schools spend more than pound;600 million a year on supply staff. The biggest agencies turn over as much as pound;60 million annually.

* One in 10 teachers may be on supply contracts, though there is no official figure.

* Top supply teachers can earn around pound;150 a day in London.

* In the past there has been little regulation of supply agencies. They are responsible for their own recruitment and for making sure the teachers they send can do the job. Four years ago the Government introduced a quality mark to set minimum standards, but it is voluntary. Some educationists have called for a supply teachers’ charter to cover schools and agencies.

* The Government, the General Teaching Council and Ofsted have all called for improved professional development for supply teachers.