A part of the puzzle, but surely not the complete answer?

Greenfinches have disappeared from my Newlands' Farm patch - fact! Last year there were at least five nesting pairs (territories), although I am unable to accurately report on how successful the breeding efforts were. These smart little finches, with their wheezing calls and aerial display flights, have been part and parcel of my patch since moving here in 2000. To suddenly discover that they've gone missing is a bit of a shock! That initial outbreak of trichomonosis was reported in 2006 and the devastating impact that this avian "myxomatosis" had upon the Greenfinch population is well documented. It seemed, however, that Newlands had bucked the trend?

28.03.2016 - a female Greenfinch at the plastic bird bath. Closer inspection reveals the tell tale signs of
Trichomonosis - a build up of food debris at the tip of the beak. 

Not so; I've been looking back through my photos and have discovered an image, from March 2016, which might shed some light on the Newlands population collapse?  "Trichomonosis" is a disease which affects the ability of the victims to swallow and digest the food and drink that they attempt to consume.  A bit of internet searching, via Google, and it soon became clear that this condition in our wild bird populations is not helped by garden feeding stations and a lack of hygiene. Victims of kindness?

A very healthy - looking male Greenfinch on the sunflower heart feeder (24.05.2015)

I have to admit that this aspect of garden bird etiquette is something I'd never previously thought about. Wild birds deal with wild situations - and then the penny dropped. Garden feeding stations are not wild situations, they are man made, as artificial as anything else in suburbia. I've had all my feeders in the sink, cleaned from top to bottom and am now happy to repeat this process on a monthly basis. Some of the advice I discovered on the internet revolved around moving the feeding station to different positions. OK if you have a big garden, rather pointless when the only safe cover is provided by our "Christmas Tree". The water in the bird baths is always changed regularly, as I also have the water in the aviary to maintain and it is simply a matter of flushing with a watering can.
Greenfinches have never been numerous around the feeders, a bit like Goldfinches, Siskin, Brambling and Chaffinch, they use the facility when they're in the vicinity. I am hopeful that the breeding birds left the area, for warmer climes, and will return in the Spring. Only then will I have a clearer picture of what has occurred locally?