Lesbian teachers tread a fine line. Every day we face jumping off the tightrope of neutrality. But how much of ourselves is it safe to reveal? Compulsory heterosexuality rules in staffrooms. Rigid coupledom, preferably married, at least with an opposite sex partner and ideally a couple of kids. You may listen to their stories about domestic life - even marital problems - but there's a gaping hole if you expect reciprocal interest. If you're under 30 they can assume that you must be looking for a boyfriend and it's easy, tacitly, to go along with it.
A science teacher colleague told her 13-year-old pupils that to be heterosexual is normal for some people, to be gay or lesbian is normal for others. Later, she tells me: "I always wish I could add, 'Like being lesbian is normal for me'."
A headteacher friend who was open about her sexuality managed for six years before she decided that the strain was too great. "It was like walking a tightrope," she says, having resigned and retrained as a counsellor. "I always felt they were looking for a side issue which they could use to undermine me."
She felt she had to excel in every way as a teacher. And like other lesbians, she felt that coming out wasn't a single act, but an on-going process which demanded courage and resilience, the support of staff and governors, and the acceptance of pupils and parents.
Even being honest with one colleague is a calculated risk and raises questions about trust. You have to feel sufficiently strong and energetic to deal with their reaction.
In my 18 years as a middle school teacher, I've sometimes thought I've been unlucky with the schools I've taught in. But I know my experiences are not unique.
My first lesbian relationship was with a colleague in the same school. We lived together for five years, worked together for two. Although we travelled to school together, bought a house, even invited staff to parties, there was no acknowledgment of the relationship, although we never met open hostility.
Since those days I've wondered if we were not sufficiently comfortable with ourselves as lesbians to let others be comfortable with us. It's easier to be open when we are confident. It is our own fears and self doubt which make us vulnerable.
My second significant lesson in being an invisible lesbian came when my five-year relationship ended and I went through the equivalent of a divorce, selling the house and finding a new home.
Now, when colleagues struggle through a break-up I find it difficult to be as sympathetic or supportive as I might be. I remember the bleakness I experienced; it seemed as if my colleagues were blind to what I was going through. No questions were asked. And I said nothing.
I became adept at presenting a shadow persona whom no one really knew and made only the barest of gender neutral references to my life outside school. It's not difficult to pass as a heterosexual if you can cope with the effect of denial on your self esteem.
Hidden lesbians are friendly but uninvolved. They reveal enough to maintain integrity, but conceal enough to avoid mainstream hostility. They talk about their "friend" not their partner. Self-censorship operates, especially in the staffroom.
I am now working again at the same school as my present partner. I feel much more visible because of this proximity and partly because as I've got older I'm much less inclined to make an effort to hide.
Our closeness must be apparent but is never acknowledged by other teachers. And yet we go on holiday as a couple and obviously spend a lot of time together outside school. We've told people obliquely in many ways. They could ask questions, but in practice they dodge the issues.
There's sometimes a tremendous temptation to be open and to challenge prejudices, to see if they would change their opinions. Or simply to watch their reaction.
It often feels a risky, frightening business. At a recent in-service training day on equal opportunities, the words sexual orientation, lesbian and gay, were received with blank silence. We were there, but to grasp the nettle and say the issue was relevant, that there were lesbian teachers in the school, took more courage than either of us had.
We also have to tread a fine line in the classroom. One friend believes that acceptance and trust as a teacher makes all the difference. She describes the 16-year-old who made hostile references to her sexuality, but whose attitude changed after they had worked together. "She's a good teacher. She respects you. Did you know she's a lesbian?" This matter of factness is perhaps more achievable with the young.
At one point last year I felt - or imagined - a slight tension in my relationship with a class of 12-year-old girls. Had they guessed, now that there were two of us? There were a few comments, grafitti on folders about dykes on bikes. I discussed it with them from a neutral viewpoint. Perhaps I should have been more open, but it may be significant that six months later this tension has gone. They've either forgotten or decided the issue is no longer interesting.
I no longer feel completely invisible with pupils. By our presence, we provide them with role models of women who don't conform to the norm. I think it's also important in the classroom to challenge linguistic prejudices around homosexuality, to help pupils understand what they're really saying, and to look at why they're saying it. Even as a partly hidden lesbian - and even on less confident days - I can do this.
I've learnt that starting young is important with all equal opportunity issues, especially gender and sexuality.
And as an English teacher I know that literature is a great starting point. I could write a book about the starting points for discussion that I've come across in a range of children's and adult literature - although there's a tremendous need for teenage literature with lesbian characters.
If we can educate pupils about the sexual spectrum then perhaps we can change lives too. Pupils who themselves are gay might then avoid some of the pain and confusion which we know hits hard in adolescence and beyond. That would be really worthwhile.
I've struggled to write this because it's at the core of myself as a teacher as well as a lesbian. The dilemma is not just the obvious one - that people assume heterosexuality - but it is the small ways in which we daily have to be silent. "The denials, deflections, defences," as another lesbian teacher and Canadian academic Madiha Didi Khayatt, has written.
Being part of and proud of a minority requires a special strength, but this has to be offset against the continual, corrosive wariness which being invisible demands. If more women step out of the shadows, it may become easier for others to follow.
Afterthought: If I put my name to this piece would I face consternation and disgust in my school? Or would it be ignored? And which would be worse?