First two shots are of the "ancient bird red-green left (the green is actually blue, but appears green; formerly also red right)". This bird has an overgrowing upper mandible. Is there a radio transmitter tucked under its tertial feathers? Can't be sure from these pictures. Nevertheless this is thought to be the 25 year old individual.
Secondly here are two shots of the other bird with the lower mandible overgrowth. This is the "younger yellow-blue vertically split band bird". The blue half of the band is facing away from the camera, but close examination of the full photographs reveals a few telltale blue pixels (see crop right). Notice that it also appears to have damaged toes/lost toe nails. This bird is assumed to be 18 years old.
Also at the zoo an unexpected year tick in the form of a Green Woodpecker in the trees on Corstorphine Hill to the east of the Living Links centre. To round off the day I decided to walk home from work through the Hermitage of Braid. I had seen a suspected Water Rail there on the 25th January and although I had checked the spot a couple of times since then it was not until today that I finally had a conclusive view of this skinny skulker.