Who is the best teacher you have ever worked with? It's a question that gets trickier the longer you think about it. "Good teaching" is a fluid concept. There is no checklist of attributes to tick off, nor is there a nice scientific chart to follow. One teacher's inspiration is often another's bte noire.
We set a difficult task, then, for the leading education figures and teachers who feature on these pages. We wanted them to choose the best teacher they had worked with and explain what made that person so great - and we refused to accept any cop-out answers.
What emerged is a fascinating snapshot of the varied types of teacher that other teachers believe to be "great". They share certain qualities, of course - dedication, a real love of helping young people to reach their potential - but there are plenty of differences, too, and in many ways those are more interesting than the common traits.
Sir Michael Wilshaw
England's chief inspector of schools
I met Veronica Carroll when I was seconded to lead a school in Canning Town, East London, in 1998. It was a school in free fall. The headteacher had had to leave. The director of education in the London Borough of Newham told me all sorts of horror stories about the place and said that nearly everything was bad. I was a bit concerned about what I would find, but it wasn't as bad as I thought it would be. Even in the weakest schools you find teachers who are entirely committed to the children.
Veronica stood out. She was a terrific teacher and she'd been there for many years. Wherever I looked, there was Veronica. She was in the corridor; she was in the playground; she was seeing the children in and out of school. She was a firm disciplinarian: tough on kids but compassionate towards them as well. She served as a role model for all the teachers there, but particularly the young ones.
I promoted her. She hadn't been promoted as much as she should have been. I used her as a resource in terms of professional development and behaviour management training for other members of staff.
Veronica could have gone anywhere, gone to an easier school and been promoted and risen up the ranks in much more pleasant surroundings. But she was entirely committed to deprived children. She never thought of moving from the school and that community. That was the way she was: absolutely dedicated, hugely energetic, hugely conscientious and an inspiration, not only to me but to all those around her.
Very sadly, Veronica contracted cancer and died last year. She is much mourned. I will always remember her.
Headteacher of Frederick Bremer School in London, where Channel 4's Educating the East End was based
When I was head of history at Fulham Cross Girls' School in south-west London, I met Mangala Nanda, the woman who, to me, epitomises the ideal teacher. When Mangala joined as a Teach First candidate in 2005, she was on a steep learning curve - the school was not easy and the pupils could be unforgiving.
Although I was her mentor, I learned so much from watching the journey she went on to become an outstanding teacher. She had such passion for her subject and was determined that the girls became curious about the world around them. Mangala reminded me of the importance of fostering strong relationships and knowing every pupil as an individual. She often argued with me about the labels I might inadvertently place on a child. And she strived to find the key to undo the barrier to their learning.
She summed up everything a teacher should be: resilient, tenacious, curious, trusting, challenging and fun. Mangala's passion was infectious and it inspires me to this day. It wasn't just the students who learned something in her lessons - I always did, too.
Former headteacher of Plashet School in East London and a trustee of the Naz Legacy Foundation. She was named headteacher of the year at the 2012 TES Schools Awards
Pam Brown was my first headteacher and she mentored me in my newly-qualified year at Connaught School for Girls in East London. Some people have a presence, and when Mrs Brown walked into a room she had just that. She was very professional, very astute and some of the things I picked up from her influenced me not only as a teacher but later as a headteacher.
When you're a head, you have a lot of responsibility and sometimes you have to sit down and think through the sort of person you want to be. You are always you, of course, but there is an element of public persona, too. So if I had a difficult staff meeting or a difficult decision to make, I would think to myself: "How would Mrs Brown have dealt with this?" Some people have a long-term impact on you and she left a lasting impression on me.
Head of history, International School of Toulouse, France
I am a history teacher, but I have always been surrounded by irritatingly talented geography teachers. The rivalry between our two subjects for the attention and affection of students is legendary, but I am grateful for the way those who teach geography well give me something to aspire to.
Simon Hinchliffe, my colleague at Wolverhampton Grammar School in the West Midlands, was permanently arranging expeditions, charity events and field trips for the benefit of his students. I escaped the searing heat of his pedagogic glow by fleeing to the International School of Toulouse, only to find myself working alongside Richard Allaway: his great talent is an endless willingness to experiment with different technologies in the classroom.
He left after a couple of years and I was looking forward to the pressure being relieved, but instead the school appointed Matthew Podbury - perhaps the best all-round teacher I have worked with. His lessons are as well-crafted as they are creative and engaging, but the amount of time he devotes to students outside the classroom is exceptional: there is hardly a break or lunchtime where he is not providing extra support and inspiration.
Matthew is every bit as enthusiastic about the pastoral side. He approaches the role of form tutor with utter commitment and, as well as visiting pupils in hospital, he has - through his sharp attention and prompt intervention - actually helped to save the lives of at least two children.
Sir Tim Brighouse
Former schools commissioner for London
It's impossible to choose just one teacher - there have been so many down the years. I could pick my colleague Nancy Dedombal, a science teacher in my probationary year in Buxton, Derbyshire, whose infectious laugh, unquenchable good humour and thirst for learning communicated itself to all her pupils. Nancy allowed me to watch and learn in my free periods.
Or should it be Trish, the languages teacher who co-taught with her glove puppet Sooty and whose behaviour control was so impressive? Or perhaps it should be Mrs Macintosh, an English teacher I met last year who is so enthusiastic about her subject that she shares where she is up to in her novel reading on the board outside her classroom.
What these teachers share is that they are energy creators. They treat pupils as the people they might become, they walk hundreds of "extra" miles, they know they are fallible and they seem to have a bottomless pit of intellectual curiosity.
Dame Alison Peacock
Executive headteacher of the Wroxham Teaching School, Hertfordshire; co-author of Creating Learning Without Limits
In my previous school, Wheatcroft Primary in Hertford, I was deputy head and Sally Fox was in her second year of teaching. We both had mixed Years 3-4 classes and we planned together every week on our shared topic.
Sally lived in a flat, so she'd come round to my house, put her washing in my machine, and we would cook together and work while having a laugh. We would plan shared class activities such as visits and experiential days. She was very good at telling stories and singing songs. We would gather all the pupils in a shared classroom and Sally would have 60 children spellbound - she could make anything come to life.
She had so much energy and excitement: we would bounce ideas off each other and have amazing fun. She had a rich sense of humour and a love of children - working with her was just joyous. Sally embodies everything I believe about making school an irresistible place to learn and she is now headteacher of Pool-in-Wharfedale CofE Primary School in West Yorkshire. They are lucky children.
Headteacher, Combe Down Primary School, Bath
It was my third year of teaching and I had joined a team of experienced teachers at Widcombe CofE Junior School in Bath. I was told about a real curmudgeon who had seen it all and was downright miserable. But he wasn't. The children in his classes adored him for his great teaching, good discipline and for being such fun. His assemblies, when he banished all other staff, always ended with the same song that had the children howling like wolves.
I learned a valuable lesson from him: you can be friendly with the pupils but you are not their mate. He was drily hilarious, especially on residential visits, and I loved working with him. He was "old school", he understood what made children tick and he taught me that a little professional distance is essential for children to flourish. Thank you, Mike Davies.
Head of learning and research, Wellington College
Philippa Hardy, head of English at Maria Fidelis School in London, changed my life. I had been a musician in a band, but we were dropped from our record contract, so I started teacher training at King's College London, thinking that I would do some tutoring to earn money. But then I met Philippa during a placement. Something extraordinary was happening in her classroom; I hadn't known that teaching could be like that. I was meant to do two teaching placements, but Philippa said to King's that her school wanted to employ me, so I did my second placement there and stayed for six years.
Philippa has a singular commitment to English literature; she privileges the written word over almost everything else. She really made me think that if you work as an English teacher you have to be passionate about your subject - that is the most important thing. And she didn't pay a lot of attention to the mindless bureaucracy and paperwork and nonsense of trying to assess teachers.
She has an overwhelming love of children; she cares for them. She's tough when she needs to be, but she is totally honest with the pupils about herself and about what she thinks about a text. Philippa is so generous with her time and is an extraordinarily charismatic person. She believed I could be a teacher before I believed it myself.
Biology teacher at Middlesbrough College; shortlisted for the $1 million Global Teacher Prize
Chris Otter was a ball of energy and one of the most enthusiastic teachers I worked with in my 23 years at Bede College (now SRC Bede Sixth Form) in Billingham, County Durham. She radiated a love of chemistry, was unfailingly positive and had a cracking sense of humour. She filled me with laughter so many times, such as the open evening where she wore two completely different shoes - not just different styles but different colours, too.
Chris encouraged students to participate in extracurricular chemistry projects, and relished the challenge of inspiring them beyond the subject specifications. However, like many excellent teachers, her success in the classroom ultimately took her out of it, as she was appointed director of the Salters Advanced Chemistry project at the University of York. Of course we want brilliant teachers involved in curriculum design and teacher training, but we want to keep more of them in the classroom, too!
Teacher and Year 1 and English coordinator, St Stephen's Infant School, Canterbury, Kent
I was a newly qualified teacher at Joy Lane school in Whitstable, Kent, teaching Year 1. Viv McGregor was coming up to retirement and teaching Year 2. I wasn't exactly a know-it-all but I was confident and sure of myself, and we used to clash over silly things such as where the PE mats should be stored. But Viv inspired me so much. Just to be in the classroom for the number of years she had been was amazing. When I watched her teach, she had these fantastic maths games that really got the children going.
Now I find myself saying to new teachers things that Viv used to say to me, such as: "What these children need are handwriting patterns." I worked with her for three years and by the end of that time the rest of the staff called me "Little Viv". She had worked in Africa, and when I left Joy Lane it was to go and work in Borneo. I had heard so many stories about working abroad and I wanted stories of my own.
Teacher at Jo Richardson Community School, Essex; director of ResearchED
The best teacher I ever worked with, and one of the few who genuinely inspired me, was Joe Dawson, a man I line-managed at Raine's Foundation School in London when I was head of humanities. He was a natural. He was the perfect example of the ambitious young teacher whose aspirations were driven by commitment to the job and the impact on children, rather than personal aggrandisement.
Within a few years Joe was head of year and head of the sociology department, and he was extraordinary at both. Best of all, he was an extraordinary teacher who managed to dance on the sweet spot between approachability and professionalism. His pupils rocketed past their target grades if they did exactly what he said, and he always knew exactly what to say to them. One day we'll have cloning sorted and we can just churn out copies of him.
Head of professional development at a secondary in the North West of England
As a new geography teacher, Claire Farmer quickly established herself as a force to be reckoned with and has gone from strength to strength in the seven years since. She brings a balance of competitiveness, compassion and conscientiousness to her work, both in the classroom and as a member of my professional development department. She is friendly and funny, but always wants to be the best and achieve the most.
Claire is reliable and resilient: she became a mentor and a peer coach and has learned how to manage those difficult conversations. She's inventive and shows initiative, offering the team ideas for Inset days, classroom strategies, subject enrichment, pupil voice and behaviour management.
To Claire, lessons really are for learning - she's relentless in her classroom delivery and will offer demonstration lessons in our observation room at the drop of a hat. She models what we expect of a professional tutor: always open to feedback, always listening to advice, always seeking to improve. If you knew Claire, you'd want to learn from her.
Retired modern foreign languages teacher
Teachers today are so fortunate that they get the opportunity to go into other people's classrooms and watch them teach. It's a fairly recent phenomenon. When I started teaching it was completely unheard of. We never watched anyone else's lesson: people's classrooms were their own territory. So Mike Smith, my headteacher at Filton High School (now Abbeywood Community School) in Bristol, was my inspiration.
I was a young teacher and I remember coming back from my break a couple of minutes late. He was standing in the doorway. He didn't say a word - he didn't need to. I said "Sorry, Mr Smith" and went and taught my class. I was never late again.
Everything about him was straightforward. He had that air of authority, but I wasn't frightened of him - I respected him. I wanted to get everything right, because he did. He was always very calm. His expectations were high, but then his expectations of himself were high, too.