Mel comes across as a supremely capable teacher at a large secondary school in Somerset. Colleagues envy her rapport with pupils, her work ethic and her above average exam results.
So why does Mel* feel like a fraud? "I constantly worry that I'm a useless teacher," she says. "I dread getting observed and being `found out'. The bizarre thing is, I have proof from past lesson observations that I can teach, but my brain tells me I was lucky or that (those observing me) have low standards."
There is a name for this pattern of thinking - it's called the "impostor syndrome". In fact, it is so prevalent that psychologists haven't stopped at just one label. Others refer to it as the "impostor phenomenon", the "fraud syndrome" or the "Achilles' syndrome".
Dr Caron King, who is writing a book about the condition, prefers to call it the "impostor anomaly". "Syndrome" implies that something is broken, she says.
"I've yet to meet anyone who doesn't relate to it in some way," says Dr King, who runs her own performance improvement consultancy, Kingswood Plus. "Even the cockiest of salesmen feels the impostor anomaly occasionally."
The term was coined in the late 1970s by American professor of psychology Dr Pauline Rose Clance. Her 1985 book on the subject explained that many impostors are perfectionists who struggle to meet their own high standards.
Another book followed later that year, If I'm So Successful, Why Do I Feel Like a Fake? by American psychologists Joan Harvey and Cynthia Katz. But Dr King believes the British are only just beginning to catch on.
"It's largely been ignored in the UK, largely because we tend to feel uncomfortable with things that come across from America as touchy-feely feminist syndromes," she says. "A lot of people over here find it unpalatable."
Dr Harvey and Dr Katz describe the syndrome as affecting people who don't feel they deserve their good reputation. "They live in fear that each new success will reveal them as fakes," they write. Up to 70 per cent of all successful people have felt this about their work at some point, they add.
The book describes a woman who attributes her success to constant work rather than ability. There is also "John", who believes that any expression of pride will inevitably end in humiliating failure.
As well as being successful, Dr Harvey and Dr Katz identify three more common characteristics of impostor syndrome: sufferers typically feel they have fooled other people into overestimating their abilities; they attribute their success to something other than intelligence or ability, such as personality, luck or some kind of mistake, and they fear they will be exposed as a fraud.
All this rings true to one newly qualified teacher. "I managed to teach a really good lesson in my interview," she admits. "But now I think the head will be really disappointed when she realises I'm rubbish and they should have given the job to someone else."
Research shows that men are just as prone to this downward spiral of thoughts, although women are more likely to talk about it. For Ed Podesta, lead teacher for ICT at Little Heath School in Reading and an associate tutor on the history PGCE course at Oxford University, it manifests itself when colleagues or line managers "drop in" on lessons.
"I'm terrified that they will criticise the quality or frequency of marking, that the lesson is dull or too snazzy, or that the children look bored or they are talking too much," he says. "It's the constant niggle that you're about to be outed as, essentially, a bit crap at what you do."
He believes it is indicative of how schools operate. Time restraints, coupled with a desire to always do better, means conscientious teachers are constantly falling short of their own high expectations.
"It's the feeling of `should do better' that you get when you look at the pile of books that you have marked on the run or at the displays in your room or when you are teaching a lesson using a textbook instead of something that might be more engaging," he says.
"We know that it's impossible and undesirable to plan an extremely active, award-winning lesson for every single class. We know that we should feel glad if we have managed to keep to our plans to mark a set of books, but we can't help wishing that there were another 12 hours in the week so that we could do things up to our own very high standards."
Nick Meredith, a coach and therapist based in Peterborough, is constantly coming into contact with people who are striving for unattainable goals.
"There is a common link between perfectionist thinking and anxiety and stress because you can never reach absolute perfection," he says. "There's a pressure between quality and time. In fact, if you do something perfectly, chances are you are not using your time very effectively."
Mr Meredith promotes the "8020 rule". It suggests that people who do something up to 80 per cent of their ability are likely to do a better job than those seeking perfection. The other 20 per cent offers such marginal benefits, it's hardly worth wasting your time on.
Unfortunately, people who feel stressed may not be able to rationalise like this. The very nature of stress reduces communication with the cortex - the more rational part of the brain. When this happens, people are more likely to think in black and white terms, otherwise known as perfectionist thinking.
Professor Stephen Palmer sees many "rigid perfectionists" in his work as a psychologist, coach and counsellor in south east London. But whereas perfectionists have a fear of failure, that anxiety dissipates as they build up experience or skills.
Those with "phonyism" - as Professor Palmer likes to describe impostor syndrome - are different. They will still remain anxious even after building up the necessary skills and knowledge.
"They continue to fear that their peers or boss will catch them out as the phoney they believe they are - if not this time, then the next time," he says. "They can't believe they have mastered something."
Professor Palmer worked with one deputy head who was comfortable with children, but found talking to parents and governors incredibly stressful. Ultimately, she had to change her underlying thinking. Professor Palmer was able to help her see that if she has the skills to teach, she certainly has the skills to communicate with adults.
Instead of tackling the problem, however, lots of teachers will actively avoid the trigger, be it going for a promotion or being observed. This can be extremely career limiting, Professor Palmer adds.
Many teachers blame lesson observations or Ofsted inspections for depleting their self-confidence. But observations can be part of the solution not the problem, psychologists argue. At the bare minimum, they help to show you are not alone.
"The problem in teaching is that we all operate in a vacuum and think that everyone else is perfect," says one teacher. "Once you get out there and look at what is going on for others, you usually feel a lot better."
But "over-comparisons" can be tricky, too. If you are surrounded by successful people, success can be normalised, making you feel inadequate. Octavius Black, co-founder of consultancy The Mind Gym, calls it the "photograph album effect".
If you look in a friend's photo album, chances are you will see them smiling and laughing while on holiday or at some other happy event. "They look as if they live the most amazingly charmed existence," he says. "People forget that they are looking at an album and not their friend's whole life. You can bet they have the same worries as you."
Any teacher in a new role or environment is susceptible, he believes. Instead of thinking you're no good, try to prove it. "Release your inner- Paxman," says Mr Black. "Argue with yourself. Find hard evidence to disprove or prove your negative beliefs."
Dr King agrees that the only person who can ultimately convince you of your worth is you. Even the most supportive colleagues are likely to be dismissed by those with impostor syndrome. They are either seen as misguided, lying or of having their own agenda.
"Colleagues have to provide evidence that you can believe in," she says. "Ask yourself, `What will it take for me to believe I'm good enough?' The proof has to be meaningful for you and context specific."
Some teachers will be able to judge for themselves whether they've done a good job or not. Others will be reliant on external validation. Mr Meredith tells these clients: "What others think of you is none of your business."
But teaching is one profession where judgment is frequently imposed upon you, whether you want it or not. Parents, Ofsted, senior management, pupils, politicians and even the media all scrutinise the work of teachers and schools. Often, they will believe they can do a better job.
Even without these external performance assessments, teachers are constantly expected to self-evaluate in order to improve. If unchecked, it can slip into self-doubt.
"Constructive criticism is good and can be useful," says an anonymous teacher. "But when that criticism seems like a slap in the face there is only so much `trying' you can do before it affects your self-esteem and physical and mental well-being."
Non-sufferers can usually contain and learn from any one criticism. But those with impostor syndrome are prone to over-generalisations, says Professor Palmer. A comment about being late on a single day, for example, could quickly escalate into a wider question about an individual's aptitude as a teacher.
People who do this fall into the "confirming evidence trap," says Mr Black. The idea is that people seek out information that supports their existing views while ignoring information that contradicts it.
"If you think you're unattractive, you'll remember the one photo that is unflattering of you," says Mr Black.
Within the workplace, the higher you rise, the more likely it becomes. "More senior people are more likely to be in the position of making decisions," explains Mr Meredith. "The weight of responsibility may make them feel like they are just winging it or waiting to be exposed as a fraud."
Headteachers may feel like they can't talk to their team about their feelings of impostor syndrome in case it is perceived as weakness.
Having a supportive workplace should help the whole team, argues Dr King. "You want to foster an environment where colleagues give honest appraisals - neither foul nor artificially nice," she says.
"Accurate feedback, backed up by evidence, is the most powerful tool to counter uncertainty. Otherwise these teachers will always set the bar of success above their actual performance, without ever knowing what the bar really looks like."
Relinquishing some level of control is another key component. To what extent can you guarantee all your pupils get good grades, asks Dr King. It is ultimately empowering to recognise that some things are beyond your control and therefore not your fault.
Sufferers can also take heart from the fact that almost everyone in the staffroom feels like this from time to time, even if they never show it. "I think the impostor anomaly is endemic in our society," says Dr King. "But it doesn't have to be debilitating.
"Instead of worrying about why we feel it, we should admit these feelings and work them to our advantage." So instead of saying, "I'm not good enough," try to work out what would need to occur for you to realise that you are, in fact, good enough. By challenging your self-perception, you can start to believe that you are a "proper teacher" after all
* Name has been changed
`I'm worried I'm useless'
TES Connect forum users are familiar with feelings of inadequacy. Here is what they have to say about impostor syndrome:
"I dread getting observed and being `found out'. I have no evidence really to back up my thoughts. I worry my behaviour management is awful. They all stay in their seats and complete all the work I ask of them. I really enjoy teaching so I don't know why I feel like this. I work hard - I'm up to date with marking, planning etc. Sometimes I think my thoughts are really irrational, then other times I actually believe it is true."
"What's bizarre is that other people seem to think I'm a good teacher, but I fail to agree, even though I've had several great lessons, which should have boosted my confidence. I'm due to cover a long-term sickness next year and I'm petrified I'm going to fail and be found out."
"I have a job interview tomorrow morning, and despite being an experienced and confident primary teacher who really enjoys the job I am terrified that the new school will think I'm awful and just laugh me out of the classroom. Illogical. But then we all feel like this. Most teachers are perfectionists - we want and expect the best not only of others, but of ourselves too."
"I've spent most of my career waiting for someone to find me out. Most decent teachers doubt themselves from time to time, and the ones who bang on about how great they are usually turn out to be full of hot air."