It took two terms for a pupil to ask Oenone Crossley-Holland a very obvious question: "Miss, are you posh?" Ms Crossley-Holland's cut-glass accent leaves little room for doubt, but a lot of the girls at her south London academy thought she must be Australian.
"They knew I was a bit unusual, but they could not quite put two and two together and see that I might be posh," she says. "I come from a very different background from the pupils, a different culture and religion. I often wondered whether I could be a good role model to them."
She eventually concluded that she could. "My own role models were not necessarily female, middle-class Wasps (White Anglo-Saxon Protestants) when I was growing up. I thought, if I could be inspired by others, why can't they?"
The cultural chasm between working-class pupils and well-to-do teachers can be stark in tough inner-city schools. But in most, teachers are likely to fit into a broadly "middle-class" category.
The typical engineer or teacher of the future will today be growing up in a family that is better off than two in three of all families, according to former health secretary Alan Milburn's much-publicised report on social mobility earlier this year. By definition, all teachers also have a degree.
In contrast, only 29 per cent of university students - and just 16 per cent of those at the Russell Group of universities - come from lower socio-economic backgrounds, even though they make up half of all young people.
Teach First, the fast-track training programme that places high-achieving graduates in some of the most challenging secondary schools, aims to get more working-class pupils "aspiring, achieving and accessing" higher education. But it does this by putting the academic elite - often those from more privileged backgrounds - in charge of some of the most disadvantaged pupils in the country.
This school-based pluralism can throw up unique challenges for teachers. Ms Crossley-Holland, 26, who trained with the Teach First scheme after attending Oxford University (like her father before her), was uncomfortable discussing class, opportunity and wealth with pupils, but it kept cropping up.
When she described Brixton in south London as "edgy, trendy . slightly dangerous but also very cool", her pupils were nonplussed. "Brixton? Brixton's cool? According to who?" they asked.
"I sometimes forget that middle-class perspectives are not universal," she writes in Hands Up!, a book about her experiences. She also realises, too late, that rhetorical questions are often an alien concept to working- class pupils.
"Did someone tell you to sit down here on these steps outside my classroom?" she asked a pupil.
"Wot? No . ".
"No, no, no. I wasn't expecting an answer. Now stand up."
Phil Beadle, a past winner of Teacher of the Year at the Teaching Awards, who taught at an inner-city school, has explored the issue of class for Teachers TV. "Working-class pupils can be perceived as being awkward, difficult or disrespectful when really they are speaking a different kind of language," he says in the film.
"You say to a youngster in an inner-city school: `What on earth do you think you are doing?' and they are likely to tell you what they were doing in no uncertain terms. You ask a fairly well brought-up middle-class child and they will probably say, `Sorry, Sir'."
By playing the right game - one that middle-class teachers like and comprehend - a better relationship is likely to be formed with the wealthier child, he argues.
Dr Gillian Evans, an anthropologist at Manchester University and the author of Educational Failure and Working Class White Children in Britain, says that teachers must have an understanding of working-class values if they are to be effective practitioners.
"A well-educated middle-class person who knows nothing about working-class life is not a well-educated person at all," she says.
If they teach in a predominantly working-class neighbourhood, they need to respect and appreciate children's social experiences on the street, in school and at home, she adds. "A teacher who knows where a child is coming from is in a better position to guide him or her to success in education."
But research suggests that many teachers entirely fail to relate to their pupils' lives. Teachers are often "uncomfortable" talking about class, despite its impact on learning, academics from Sussex University have found. Although pupils identified positive relationships with teachers as crucial to their learning, teachers had "deeply ingrained" negative views about working-class children and their parents.
"Teachers' perceptions of pupils' achievement and their expectations of them were influenced by social class," reported Louise Gazeley and Mairead Dunne in Addressing Working Class Underachievement.
"Stereotypical views of middle-class and working-class pupils and parents perpetuate disadvantage and contribute to the underachievement of some working-class pupils."
These sometimes unconscious prejudices could contribute to high levels of underachievement in the most deprived communities. According to a report from the Conservatives last year, more than half of secondary schools in the poorest parts of England fail to get 30 per cent of pupils passing five good GCSEs. In the richest areas, just 3 per cent of schools fail to hit that benchmark.
Charlotte McCormick, 23, is determined to reverse that trend. She trained with Teach First before joining staff at Haberdashers' Aske's Knights Academy in Lewisham, south-east London, an ethnically diverse school with higher than average levels of pupils on free school meals, English as an additional language and special educational needs. Not at all like Giggleswick School, the private school in North Yorkshire where Ms McCormick was educated.
"The pupils never escape Lewisham," she says. "I used to live in Borough (about five miles from Lewisham), and they thought the commute was ridiculous. They thought I would have to catch a plane to visit my parents in Yorkshire."
Despite the obvious differences in background, she believes that teachers do not have to be a prototype of the people they teach. "I have never been a victim of knife crime or been pressurised to join a gang, but I do know what is morally correct and can advise pupils accordingly," says Ms McCormick, who has been nominated president of this year's Teach First participants.
"Teaching is not about background, it's about personalities and being a good teacher. I never felt my background hindered me."
That's not to say it has all been plain sailing. In Ms McCormick's first week at school, her car keys were stolen from her desk drawer, and she found some behaviour hard to manage. But she always picked herself up and came back to class the following day. "You have got to show the kids you care, no matter what. Eventually, they learn to respect that."
Lauren Hucknall, another Teach First graduate who teaches English at Djanogly City Academy Nottingham, agrees. She was initially frustrated that her pupils did not, or would not, share her love of literature, but learnt how to relate it to their lives.
"What I found exciting, they didn't," she says. "Trying to teach Romeo and Juliet to my Year 10 class was challenging. They couldn't see why they should learn Shakespeare or what relevance it held for them. I eventually started to focus more on some of the characteristics in the play, such as the fractious relationship between parents and their children, which made it less alien to them."
Slowly, Ms Hucknall became less alien, too. She was a pupil at a state school in Derbyshire before attending the fee-paying United World College in the US, a positive experience she shares with her pupils. Although neither of her parents went to university, they encouraged her to get a degree.
"A lot of kids have to deal with stuff that I'll never be able to relate to, and I wouldn't want to relate to," she says. "But I've managed to build a positive relationship and classroom culture based on trust. I hope the pupils know that I really want to help them."
This kind of attitude is crucial to boosting standards, especially in more deprived areas, says Barry Day, the chief executive of the new Nottingham Academy, which is set to become the biggest school in Europe with 3,600 pupils over three sites. Before he took up his post, he was the headteacher of Greenwood Dale School in Nottingham, one of three schools that now make up the academy.
When Mr Day arrived at the school in 1992, 12 per cent of pupils achieved five A*-C grades, excluding maths and English. This year, 97 per cent hit that target.
"When I joined, the school was in a dire situation - it couldn't get much worse," he says. The school is in one of the most disadvantaged communities in the country, and some teachers felt that the pupils were incapable of doing any better.
"There was a `What can you expect from these kids?' kind of attitude." When he announced to staff that he was going to replace the school's old- fashioned BBC microcomputers, which were mostly used for games rather than anything educational, with smart new PCs, one of his senior members of staff said the pupils would never use the PCs. "You won't, but they will," replied Mr Day.
Since those early days, there has been a "clamour for learning", Mr Day says. "Irrespective of their background - that of the pupils' or their teachers' - the kids here know the staff care about their welfare and their academic success. In the past, teachers didn't believe pupils could do any better. That attitude has been totally turned around."
It helps that a lot of the teachers are former pupils of Greenwood Dale, embodying the "you can do it too" approach of the school. It also recruits people from the local community, often as learning mentors.
"It's good for pupils to see lots of adults in school who come from the same background as them, but there is a great deal of variety among our teachers. Ideally, you have staff who are representative of the student body who also care about the pupils. But of the two things, caring is the more important."
Ruth Carney, 28, is not Asian like most of her former pupils at Cranford Community College in Hounslow. Neither is she a refugee fleeing war-torn Somalia or Afghanistan like others in her classroom. Instead, she went to a private junior school and then a state secondary in "leafy" Reading. After getting a degree from Warwick University, she joined Teach First and became an RE and citizenship teacher for two years, before helping to set up an educational charity, Jamie's Farm, last year.
"I was expecting tough, but a sort of Grange Hill type of tough," she says. "I hadn't reckoned on just how hard some of the kids had it."
The pupils expect to work, but not necessarily in highly paid jobs, she says. "A lot of their parents are baggage handlers at the airport and there was a lot of excitement when Terminal 5 was built at Heathrow because that meant more work."
Some teachers say that pupils respond better to those from their own culture, such as Asian boys to female Asian teachers, adds Ms Carney. But she thinks it is more important to be a strong, safe, dependable adult in their lives. "You have to prove yourself as capable. Then they will respond to you."
But the class issue should not be underestimated, suggests the Sussex research. If teachers are to have higher expectations and aspirations for working-class pupils, student teachers need to reflect on their own attitudes and values during training, it suggests. Initial teacher training (ITT) should help students recognise when class "influences actions and interactions, especially at an unconscious level", it states.
This is already happening during ITT to an extent, says Kate Aspin, senior lecturer in education at Huddersfield University. It recommends that trainees use "standard English" to help with communication and encourages students to have high expectations for all.
"Attitude is the most important factor," says Mrs Aspin. "If a trainee is willing to learn, has high expectations, wants the best for all pupils and treats them as individuals, then they should be able to teach anywhere."
Mrs Aspin has taught in both working-class and middle-class areas across Lincolnshire, Manchester and Yorkshire. "Some parents found me posh, others not posh enough, but the children took me as I was," she says.
Some primary-school pupils said she "talked funny", which prompted interesting discussions around accent and dialect. "You have to acknowledge background, but the professionalism aspect, such as attitude and communication, has to be central."
Mr Beadle agrees that it would be a "ridiculous, classist slur" to suggest that working-class teachers have a monopoly on good teaching in deprived areas. "However, there is a degree of cultural knowledge required to properly empathise with the baggage many working-class pupils bring to the school gates. Merely by accident of birth, middle-class teachers are unlikely to be in possession of this knowledge," he says.
"While a middle-class teacher will be able to engage working-class pupils, perhaps even to make some fairly bloodless connection with them, understanding them, and their culturally conditioned lack of apparent aspiration, can be more difficult."
Ebbing away at self-esteem is a ridiculing of working-class culture in society. The birth of "chavs", as parodied by comedians such as Catherine Tate, can leave working-class people feeling patronised and laughed at. Belittling the antics of Wags, footballers or wannabe celebrities in the tabloids further undermines working-class pride.
Schools are not always working-class havens either. Some claim they are fundamentally middle-class institutions where working-class pupils - with all their class-based language, attitude and beliefs - will always be swimming against the tide.
But Tom Bennett, who teaches at Raine's Foundation School in Bethnal Green, east London, insists that class is not so clear-cut any more. For example, a teacher who comes from a family of Geordie miners with a taste for opera and an inclination towards the Conservative party won't fit neatly into any class box, he says.
He agrees, however, that self-belief is especially fragile among working- class pupils. "There is a learnt assumption within more privileged homes that their children will of course do well in life," he says.
Teachers from all walks of life can invigorate this waning self-belief, insists Barry Day, no matter where they are from or who they teach. In his consultancy work, he has come across headteachers who will only enter their working-class pupils for level 1 courses, meaning they can do no better than a grade D.
"That sort of attitude, which permeates down from the head to the rest of the school, sends out a strong message about aspirations and where pupils belong," he says. "It must be countered by staff who really believe their pupils can do better."
That belief is not limited to teachers who mirror their pupils' backgrounds. What seems more important is that teachers are thoroughly committed to ensuring pupils reach their potential. In the words of Mr Bennett: everything else is chaff
16% of teachers come from families or backgrounds with higher managerial and professional occupations.
30.8% come from families or backgrounds with lower managerial and professional occupations.
17.2% come from families or backgrounds with intermediate occupations (eg firemen).
8.3% come from families or backgrounds who are small employers.
6.4% come from families or backgrounds with lower supervisory and technical occupations.
14.6% come from families or backgrounds with semi-routine occupations.
6.3% come from families or backgrounds with routine occupations (eg refuse collector).
0.6% come from families of those who have never worked or are in long- term unemployment.
Source: Students on teacher-training courses 200708; data recorded by the Higher Education Statistics Agency. NB Only 38 per cent of those asked about their background (29,965 students out of a total 79,040), stated it.