I discussed it with a colleague quite recently - we do get on well, and we do the same role, and comments made by my manager when he was announcing my payrise in a 1-2-1 made me suspect there is a gap. So (about a month after I first thought about asking), when colleague and I were alone, I asked him, what his salary is, from an equality perspective, as I'm the only woman in the department. There is about a 13% difference, and as I'm more productive (and the one good thing about their micromanagement is that I can prove that,) and better qualified and similar experience, as it's meant to be performance-related, I should be on at least the same, if not more - however, I'm not making a fuss just now, as I'm about to start a secondment to another department. One fight at a time.
I did ask about pay at a previous company, having found out a more junior colleague was on more than me. The response I got then was that discussing pay was a sackable offence, which closed the conversation. This would have been around 1999/2000. When the department was pay audited a couple of years later, I got a 26% rise to level me up, so I was right to have questioned it.
Totally agree there should be more pay transparency.