In the last few years, whenever I’m asked to tick a box on diversity data, I declare that I’m bisexual. It only comes up when I’m filling out the diversity monitoring form for a job application, or filling out the annual staff survey – or registering in a new department, as I recently have done on the HR system in Defra.

I imagine most people assume I’m heterosexual. I’m very happily married to my husband, Paul, and we have two children. My bisexuality is, I used to think, nothing to do with the people I work with. I don’t particularly want to be speculated about or judged. But I had a painful experience which now makes me wish others before me had been more open.

Being bisexual was only something I really started owning up to – even to myself – after I’d been a civil servant for some time. I thought that being bisexual was not welcome in the upper echelons of the civil service.

Early on in my career, I had been developed vetted, the highest form of security clearance – which most permanent secretaries need, and anyone who works in Downing Street.

It was a long, three hour interview, conducted by a retired male police officer working for the Foreign Office. We sat in an airless basement room somewhere around Horseguards. He went through my bank statements, asked me what I’d got up to at university and asked whether I had any ‘lesbian or other deviant tendencies’.

This was in the early 2000s. I knew in my head that gay people were successfully developed vetted. I knew that it was inappropriate that he had framed his question in that way. But I didn’t make a fuss. I got my security clearance. But later, acknowledging my bisexuality, I started avoiding jobs that required my developed vetting to be renewed.

After a few years, I got to the point of renewing my ordinary security clearance. There was a bit at the end of the form that asked me to declare anything else that might be significant. It led to a couple of sleepless nights. If I did not declare that I was bisexual, would I live with myself for lying? Were people like me allowed in the senior civil service? Might I lose my job? Would they think I had lied before, when I hadn’t even been out to myself?

I wasn’t aware of any other bisexual people who were in the senior civil service, and the last time I’d looked at my department’s diversity data, the statistics suggested that there was just one – and I knew that was me, as I’d ticked the box!

I imagined that other bisexual people had been like me, believing it wasn’t their workplace’s business. They hadn’t declared their sexuality on the diversity forms, and they hadn’t reported the odd bit of discriminatory language. But because I had been quiet, and they had been quiet before me, someone had allowed that silly question to be asked in the developed vetting interview.

Writing this blog led me to contact the Cabinet Office about vetting policy. They say that nowadays, sexual behaviour is treated more maturely and sensitively in the developed vetting process. They are very keen to encourage LGBT people to go through vetting. Every vetting officer receives diversity training. Complaints about the vetting process are treated very seriously. And this year, the whole system is being revamped with a greater emphasis on customer service.

What’s more, MI5 was just named by Stonewall as its top employer of the year for 2015, ahead of Lloyds Bank and Cardiff University. But I strongly suspect that it took people speaking up, and even ticking boxes, to get things changed.

I care passionately about having a diverse Civil Service. This isn’t just about sexuality. It’s about all of us. We can’t be good policy makers, and we can’t deliver good services, if we assume our perspective is the only one going. The reason why we all need to know the numbers on diversity characteristics – on sexuality, on disability, on ethnicity – is that sometimes it’s only the hard facts that can help create the case for change. My story also shows that the facts reassure people that they are not alone.

So, I have a plea. Declaring your sexuality, your disability, or your ethnicity on a confidential form is much easier than what I’m doing right now in this blog. The data in that checkbox can’t be disaggregated and identified back to individuals on the Defra HR system. I’m saying this particularly for those whose diversity characteristic is hidden, like mental health, a hidden disability like dyslexia, or sexuality. Ticking that box is a way of reaching out and saying, ‘You are not alone’.

This blog was originally published on the Department for the Environment, Food and Rurual Affairs’s intranet. It is republished here with permission of the author.