As thousands of teachers join the rush for early retirement, they might like to consider the career of Ellen Niblett, still teaching at the age of 97. Born with the century, on January 1, 1900, she started her career during the First World War and retired from full-time teaching in 1965. She continued supply teaching until her employer - the London borough of Haringey - told her shortly before her 70th birthday that it was not its policy to employ teachers over the age of 70. Now, as the millennium and her centenary approaches, she still tutors children at her home in Muswell Hill, north London.

“Say I help them,” says Mrs Niblett, her hair newly set, her gaze shrewd and straight, her telephone ringing frequently. “Don’t make it too formal.I do it because I’m interested in it, and it keeps my brain active.”

Many teachers half her age feel they’ve had enough nowadays. Twenty-five years in the classroom, say youngsters in their late forties, takes it out of you.

Ellen Niblett began apprentice teaching when she was 16, in a Kent classroom where an open fire burned in the grate in the winter and while many male members of the profession were being slaughtered on the western front. Eighty years on, hasn’t she had enough?

“I could easily sit here and do nothing and become a vegetable,” she says,from the chair in her sitting room. “I do crosswords and I play bridge. The children coming is a fresh lot of people coming to the house. And the mothers come, and sometimes the fathers, and I get into conversation with them. It takes my mind off other things.”

Her room bears witness to her life. The sideboard is crowded with family photographs, including one of her grandparents whose lives stretched back into the early 19th century. There are postcards from Hawaii and Thailand and the Skelligs stuck around the mirror, and a crocheted snowflake made by a former pupil now teaching in Canada. The room is quiet apart from the slow tick of the clock, and she’s never bothered with central heating.

Ellen Elliott, as she was then, began her own schooling at the age of three. The only child of shopkeepers in the castle-and-cathedral city of Rochester in Kent, her parents sent her to school early because they thought it would be good for her to mix with other children. At 10, in 1910, she went to Rochester Grammar School on a scholarship provided by a local benefactor. “I don’t think there was a great deal of socialising outside school between the fee-paying pupils and the others,” she recalls. “There was a certain amount of class distinction, and one or two of the staff rather emphasised that. ”

Discipline was strict. A teacher was posted outside the cloakroom at the end of the day to check that girls didn’t leave without putting on their white gloves; if they wanted to walk to school with a friend, their mothers had to write to the head for permission. “The idea was that you shouldn’t block the pavement,” says Ellen. “There was a long list, but it seems ridiculous because if you quarrelled with your friend, as children do, those names had to be taken off.”

After taking the London matriculation at 16, Ellen became a pupil teacher at a local primary school. When had she decided to become a teacher? “People who went on free places to the grammar school more or less automatically went on to teaching,” she says. With the war causing staff shortages, she soon found herself teaching alone, in a section of the school separated from the headmistress’s office by just a curtain. “I was in charge of a class but I didn’t draw a teacher’s salary,” she says. “It was the war years. I resented having to do so much, but I’m sure it was very good for me. I still think it’s a very good idea to spend six months or a year in the type of school in which you hope to teach.”

She went on to teach for a few months in a boys’ school, where she was given an unruly class. Their previous teacher, an alcoholic, had been sacked and then committed suicide. “You can imagine what the boys were like,” she says. “He’d had no discipline at all. I put my hair up, to give myself a little bit of authority. But it was hard.”

After a year off with illness, Nellie - as she was then known - went to Goldsmiths College, London University, to do her degree. It was 1919, and among her fellow students were a number of decommissioned army officers returning to civilian life. Only two of the 16 young women who began the degree course finished it, and she was one of them.

Like the other graduates, Ellen Elliott had two seats reserved for her family for the ceremony at the Albert Hall, in which students knelt in front of the chancellor to be awarded their degrees. But her proud, uneducated father didn’t come. “He knew very well he would start weeping,” she says. “I got what brains I had from him, but he never had the chances I did. Mother came. She was different.”

Teaching was different too. In 1922, Ellen began her first proper teaching job, in a private girls’ school in London. Her annual salary, drawn six times a year, was #163;150. “I was very happy there,” she says. “The staff were all fully qualified, and the standards were quite good. I’m still in touch with some of the girls I taught there, although they are now in their late 80s. Several have died, of course.”

The school was closed on the outbreak of the Second World War, and Ellen Niblett - married by that time to a metal merchant and with a son - started work at a prep school in 1943. The next year, under the 1944 Education Act, it became a state primary school and she stayed there - initially teaching classes of around 50 children - for the next 23 years until her retirement.

She brings out an album presented to her on the occasion of her retirement by the staff at Tetherdown Primary School in Haringey. The school is still open, and recently scored highly in the first published batch of national test results. There is a group photo of the staff taken in 1965. “That one’s dead, that one’s dead,” she says, pointing to her erstwhile colleagues with their shift dresses and little brooches and confident smiles. “And that one. Isn’t it awful.”

There are photos of the pupils too: a formal one, a snap of a group of girls in vests and gym knickers, looking toothy, and one of a group country dancing and playing recorders. They’ve all signed their names in their best rounded writing. Among the shop-bought retirement cards, featuring swans and lake views and floral arrangements, there’s a card drawn by a child, of an armchair. Mrs Niblett had a letter from the artist at Christmas - he’s a croupier in Las Vegas now. “We keep up a very desultory correspondence,” she says. “He’s trying to write a book because he now has a child and would like to get away from Las Vegas. ”

It is probably the wrong question, but I ask Ellen Niblett, the product of the Victorian schoolroom, if she likes children. “I get on reasonably well with them,” she says. “I am a disciplinarian. I don’t let children do as they like.” She doesn’t know much about the national curriculum, “except that it incurs a tremendous amount of paperwork for the staff. It appals me, the amount of paperwork.” She sees nothing wrong with competition - “life is competitive. I can’t see that it’s wrong tocompete” - and upholds the value of traditional skills: “I don’t think there’s any objection to tables. Even calculators can make mistakes.”

The primary children she helps come by word of mouth. She brushes up their spelling and grammar and introduces them to a little French to give them confidence when they start secondary school. She takes more time over the preparation of the lessons than the hour she spends with each pupil, and in maths, she says, “I give them slightly more complicated problems than they would get at school, to try to induce them to think.” She has four pupils at the moment, and charges a modest #163;6 an hour.

Ellen Niblett walks with difficulty and cannot get out of her house unaided. She goes to Wales three times a year, to stay with her son and his family. At home, one neighbour buys her fruit and vegetables, while her home-help brings stamps, and the yeast she needs for breadmaking. Another neighbour takes her to the hairdresser, and gets odd things from the supermarket. “I’m not dependent on any one person,” she says, and before I leave I sign the visitors’ book, change a light bulb in the cellar and put out the newspapers for recycling.