The one certain place you will find the Goldfinch at this time of year is perching amongst the dead Spear Thistles. They eat the seeds found in the dried heads of the thistles.
The trick is to get close to the birds to be able to take the photographs. Spear Thistles are mostly out in the open in the parkland area where I normally walk and approaching them without disturbing the birds is the difficult part. One should never intentionally disturb birds when they are feeding especially with the extreme cold temperatures at present. They need all the food they can get to maintain energy and body heat. I kept my distance for these shots, even so these birds are instantly recognisable in any surroundings.