I would suggest a thorough wash down and decontamination of the bird feeders and throwing away of the niger seed just incase this is some kind of fungal or bacterial thing.
Found the following two links with a quick google search - looks like there have been very similar problems in the USA in previous years - another possibility is a type of conjunctivitis.
This is very strange, last week, we found a Bullfinch (young) dead on our path, we initially thought she had struct something, but she didn't recover, there were NO sign of injury or disease, very strange, as far as were aware both parents are still present as they visit our tree daily.
First ever dead bird we have found in our garden, and strange with no injuries !
Hi Damon
Thanks for info, will inform my aunt and do as you suggest. Haven't checked if more have died but I do know she washes her feeders every week and stores her food in air tight container. Watch this space.
Shazz