Yet today Mrs Ryan appears the archetypal village schoolmarm, out in rural Norfolk running Shelton primary, which has only 36 pupils. Friendly and briskly efficient, she knows everything that is going on within her domain. Which is just as well. Mrs Ryan is the only full-time teacher in the tiny two-class school, where she works alongside and manages three part-time teaching staff and a part-time secretary.
It's been a varied career for someone who left school at 16, married at 19, had three children and adopted one, did her teacher training as a mature student with a family to raise and started teaching when she was 30 - inspired by her teacher husband David. Mrs Ryan then spent 21 years at the same school in Scunthorpe, Yorkshire.
A deputy headship seemed the logical progression after a while, but she was told she had three things working against her: her age, her health (she had her neck in a collar for a year) and her union activities. She decided to make a virtue out of a so-called vice and plunge into union politics, getting involved in AMMA when primary-sector membership, in what had traditionally been an organisation for secondary and grammar school teachers, started to increase in the mid-1980s.
Mrs Ryan's employer, Humberside County Council, gave her a year's secondment for her presidency of the ATL, which allowed her time for running the association and ensuring that members' interests were being served.
"It was fascinating to be responsible for 130,000 members as there were then (there are now 150,000) and, at the same time, going round the country to education meetings, conferences, visiting lots of schools," she says. "I had said from the outset that I wanted my work as president to be based on real life, dealing with the real problems of teachers in the classroom."
She appreciated the variety after her long stint of teaching. "You get into a situation as a primary teacher where you're stuck in your own classroom and never get a chance to see the wider educational world. That's what spurred me on to getting involved in union activities, courses, conferences and meetings and the national education scene. Being able to contribute on a local and then a national level gave me a broader view of education, one which I wouldn't have got otherwise."
Her move to an isolated rural school couldn't be more different. Even though her school is part of a regional small school cluster, her sphere of influence and ability to circulate outside the school is limited. But she relished the challenge of taking on a headship for the first time at the age of 50. "The difficulties of working in small schools aren't really acknowledged," Mrs Ryan says.
A major difficulty is working on a budget that is calculated on the numbers of children on the roll, even though heating, lighting and maintenance costs are the same as larger schools. Working with insufficient funds means having to take decisions that inevitably increase her workload.
"Last year, we couldn't afford to buy back the whole Small Schools package that the local education authority provides," she says. "So the governors and I had to decide which services we couldn't do without and would have to buy in, and which I'd have to manage on my own. It made my workload heavier, having to take on building and cleaning, grounds maintenance and technical support. Since I teach full-time, those extras had to be done at weekends. This year, the governors have decided to buy in the full package, which means that the books and equipment budgets have had to be cut."
Another problem is having at least three bands in each age group, divided into two classes. "The biggest difference is the amount of time spent in planning and preparation because of the range of ages in each of the two classes, " she explains. "Planning for six five-year-olds is the same as planning for 30, except that in our family-grouped classes of three bands in each age group, we do three times as much planning and preparation for the infants and four times as much in the juniors."
Among the children are two carrying statements, four who are at stage 3 (pre-statement) and one gifted child. For the school to function, children from reception upwards learn to work independently and collaboratively, with the more able children helping those who need it. More formal help comes in part-time from the LEA's learning support team.
A juggling act is needed to deliver the curriculum effectively, but "it's all in the planning". Mrs Ryan takes the infant class of children aged four to seven for four full days, concentrating on basic literacy, numeracy and science. Her part-time infants teacher works on history, geography, crafts activities and short tennis for the other day. Depending on the topic work under way, she will also take on humanities areas.
In the juniors, a newly qualified teacher is on duty three times a week, working alongside a more experienced teacher one of those days. "This way, they can co-ordinate work and do science and technology together, which are subjects that require more adults per child," she explains. "The experienced teacher has overall responsibility for the class and teaches maths, while the new teacher is in charge of English and religious education. Other subjects are shared, which requires a lot of planning and dialogue."
Taking on a newly qualified teacher has advantages in terms of enthusiasm and innovation, but it means pressure on the rest of the staff who need to advise and cover for her when she goes off for extra Inset. But Mrs Ryan is not deterred. "We just go for after-school Inset," she says coolly.
It's not all grind. Small means intimate. Parents come in every day to help with curricular and extra-curricular activities, volunteering their skills in music, sports, reading and science under teachers' supervision. Two years ago, the 25 families who send their children to the school raised Pounds 14, 000 to have indoor toilets built.
If being the headteacher at Shelton primary has effectively taken over Heather Ryan's life, it's a development she clearly enjoys. "I love being here, " she says. "I drive across the Common at 7.30 every morning and I see barn owls, weasels, shrews and rabbits. It's a bit different from Scunthorpe!"