Thanks everyone.
I know that I have some protection under the disability discrimination act but the corporate drive to save money and reduce absence just doesn't respect the difference between people who have an illness (physical or mental) and people who are "sick" and take 5 days when they're better in 3 days or who have a hangover or a domestic crisis.
Last year, before the depression, I had 5 days off for an operation and then 6 months later I had 5 days off with concussion. That got me a red light for exceeding the corporate average. Both times I went back to work sooner than the docs recommended but that wasn't good enough in this target driven world.
I wouldn't care, but I've worked for them for 11 years and most years I've not had a day off for ill health.
I can understand the need for the organisation to save money (I'm lucky enough to get full pay for 6 months sickness and then half pay for another 6 months) and I can understand their need to know whether I intend going back. But my job doesn't get covered while I'm away, so what doesn't get done will most likely be waiting for me when I get back and knowing that doesn't help much. I just feel like I'm a number or a failing target and not a person.

Wow, I didn't expect to vent quite as much as that, and I hope that having the mental capacity to rant is a sign of the depression shifting.