Barry doesn’t exist. His traits do, of course, exist in what my leadership courses taught me to call the "blockers" – the cynics; the seen-it-alls; the awkward squad. Only, it’s the people like Barry who, without need for recognition (indeed, while apparently recoiling from it), have given me the strength, the perspective and, yes, the quiet kindness I’ve needed to carry on. If you teach, I sincerely hope you are lucky enough to work with a Barry.

Barry doesn’t give much away. Among the first things anyone new to the school community learns is not to touch Barry’s mug. It’s the one with the ginger cat. He can be found at "Barry’s seat" in the staffroom between 8.12am and 8.23am and again between 11.07am and 11.23am, reading his newspaper.

Barry is the subject of much speculation in the school community. He’s got to be up for retirement soon, surely? Nobody knows how far off it is, but it is generally known that the grandchild of one of Barry’s former students started in Year 7 in September. Barry wears cufflinks. Barry doesn’t "do" mobile phones.

Barry greets the colleagues who wish him good morning (around a third of them) with a nod as he makes his way to his classroom. Barry doesn’t smile often. Barry has a bowl of fruit on his desk and a faded tapestry behind it. He has a peg for his jacket and stores his bicycle lock in his bottom drawer. There aren’t really any other clues about Barry in the classroom. He doesn’t give much away.

Barry’s known in SLT as a "maverick" – spoken through gritted teeth in much the same tone as one might identify a "vigilante". There have been a few "difficult conversations" recently. Last month, Sam, the deputy head, had to "have words" about a parental complaint. The parents of a Year 10 boy are deeply aggrieved at Barry’s "victimisation" of their son. Barry, aware of the recent drive on healthy eating, had meant his words about Pringles for breakfast and expanding waistlines to be in jest. He acknowledged the room for alternative interpretations but didn't say more.

A teacher loved by the pupils

Barry has mentored many trainee teachers over the years. Barry is no longer a member of the "growing new talent" team because of concerns that he doesn’t consistently embody the school’s mantra: "aspire to excellence". If he’s disappointed, he doesn’t show it.

For the past decade, Barry has run a poetry club every Wednesday lunchtime. He has been scolded by the stressed-out head of geography recently for "taking her key marginals away". He understands. She’s under pressure to get grade 5s, after all. SLT have omitted the club from the cultural enrichment passports they’ve recently introduced because it "doesn’t have a tangible impact on outcomes". Students still come. Sometimes he even pretends he hasn’t seen them. But he doesn’t give much away.

Last Friday, Barry was called to the headteacher’s office to discuss "growing concerns about his compliance". She referred to a notepad on which she had apparently scripted her words. Professional standards were cited. He was asked to explain the following:

• Why was he seen blatantly reading a book during the latest twilight Inset on meeting the needs of more able learners?
• Why had he failed to give the requisite (academy policy) three merit points in his last Year 8 lesson, instead recording an unprecedented 20 rewards on the system?
• How had he failed to comprehend the potential professional misconduct charge incurred by his spending his own money on lunch for students at the latest British Museum trip, encouraging them to eschew their pre-labelled pupil premium packed lunches?
   

Barry nodded and asked if he was free to leave. He babysits for his granddaughter on a Friday from 5.00pm. He doesn’t give much away.

When he cites TS Eliot in class, it is for Barry’s students’ eyes and ears only. (When he is observed, he sticks to worksheets.)

In the classroom next door, Salim, an exhausted NQT, dreams of lighting children’s passion for poetry as Barry once did for him.

Barry's lessons start with “Let us go then, you and I…” and his Year 9s are pin-drop silent. They are not engaging with this week’s "initiative focus", whereby they have to tick off "learning for life" characteristics on their passports, as will be discussed with the assistant headteacher in charge of personal development this coming Friday afternoon.

School budgets are tight. Barry is expensive. It would appear that Barry is resisting the gentle nudge to become "natural wastage"; one more in a line of departing and non-replaced teachers. But Barry doesn’t give much away.

Barry’s fruit bowl provides the only sustenance that many of his students get in the morning. In the drawer above his bicycle lock, he keeps cereal bars, and in the cupboard at the back of his classroom, he keeps spare school shoes. Those whose shoes wear out know where to come. Those who are hungry know where to come. Those who just need somewhere quiet to sit and feel safe know where to come. Barry doesn’t give much away.

Yesterday, just down the corridor, Maryam, three years into her career, was having one of those days that chew you up and spit you out. Barry didn’t give much away, but when she came back from trying (and failing) to have some lunch, there was a chocolate bar and a fresh cup of tea by her computer.

Barry is supposed to mark in green. Barry still marks in purple.

Dr Emma Kell is a secondary teacher in north-east London and author of How to Survive in Teaching