Rich, correct, it is a confusion species, but the ring around the eye on the Serin is too distinct, especially at close distance
Thank you Ash, unfortunately the garden is about a mile north of the SOS recording area (WNW of the A38), so just in Avon.
The birds appeared in the mornings for a week or so and surprised me by being less timid than Chaffinches / Greenfinches. Quite content to feed together on the small seeds, but not with other birds.
This evening I put three pictures in front of 'the Boy' - Yellow Hammer, Siskin and European Serin as a cross-check. He immediately identified the Serin.
Have a look at
and scroll down to 1st march for what Serin looks like at this time of year.