This is something I've come across before. With a very front orientated brake bias the fronts do most of the work and with a car that has a high COG the transfer of weight forwards under hard braking increases this even more to prevent the rears locking when unloaded. This leads to nice shiny front disks but rust ingress across the surface of the rears as the pads get ground away by the hard and abrasive rust. Ideally I'll replace the disks and pads but not sure if it's worth it as a they hardly do any work anyway and the process of rust will just start again. What's the state of other peoples rear disks? 2012 TDV8 Vogue (L322)

I would suggest that your rear brakes are not working properly. The braking surface should be bright and shiny just like the front.

That's my other concern - air in the rear system or seized. The center of the disks are shiny enough so the brakes are applying some force. 2012 TDV8 Vogue (L322)

If you had air in the system you would have a spongy brake pedal mate. Get yourself a cheap infra red thermometer, go for a drive and use the brakes and then take a reading. It will give you some idea of what's happening. Fronts will generally be a bit hotter than the rears but not a vast difference if all is well.

Brake pedal is firm. Done a touch test on the wheels after a drive and nothing out of the ordinary i.e fronts warmer than the rears and no sticking calliper also disks each side same condition. If it wasn't for the tricky handbrake setup I'd just replace them and expect new pads on new disks to keep a consistent surface across the friction area. 2012 TDV8 Vogue (L322)

Handbrake set up is not tricky mate. If it's working just leave it. You might have to back off the adjusters to get the discs off but don't bother with all that set up malarkey it tells you to do.

The rear callipers are probably seized in position and not operating hence the rusty discs. The discs should be shiny / polished. If indeed the callipers are seized the brake pedal would be solid. Nothing raised at the last mot?.
You really need to dismantle each of the rear callipers, chances are the pads are seized into the carriers.

Just to be clear the centre band of the disks are shiny so not convinced they are sticking but will pull the callipers off the carriers and see if a good clean up and application of ceramic brake grease does. Then again if I don’t need to mess with the adjustment and bedding in procedure I may as well go straight to new disks and pads. 2012 TDV8 Vogue (L322)

Yep, new Discs & Pads required there.

Totally shot mate.

Yes totally agree… Need changing BUT!, paint the new parts before you fit them so, the disc bell and the outer fins and that way the rust shouldn’t come back on the new brakes…
I fitted new rear discs & pads on my grey 405 and drove it for 4yrs before selling it and the rear brakes still looked fantastic… A job well worth doing before fitting 👍

Delphi set from AA factors will be my choice unless anyone has a better suggestion? 2012 TDV8 Vogue (L322)