How much monitoring is too much?

I received an internal e-mail last week, stating that not all staff had not provided the diversity data sought on our internal HR on-line system. Apparently, a new section on sexual orientation has been added.

Now I fully understand that my employers want to ensure that they don't discriminate, but whilst ethnicity and disability are obvious, and there are good grounds for having disability data so that proper adjustments can be made, I'm a mite uncomfortable about their need to know my sexual orientation. It doesn't impact on my ability to carry out my duties, there is legislation to prevent staff from discriminating but it falls into the area of my life marked 'none of your damned business'.

There is almost certainly discrimination against some non-heterosexuals within HM Revenue & Customs. I haven't personally experienced any, but the likelihood is that it exists. But isn't it easier to leave people's private lives just that?...