Although the bird appears to have now disappeared, the question over it being a genuine wild bird still remains. With the amount of White-throated Sparrows hitching a lift on the QEII recently it seems that if it is accepted as a wild bird it must surely have been ship assisted. House Finch is an introduced species to Eastern America and is generally sedentary although in the eastern part of the USA some of the population undertake a partial migration to the south and south-west of the range, with adult females moving longer distances on average than males. The Lands End bird shows a lot of yellow above and below the eye and looks like the race frontalis although yellow variants can occur in all races. Anyway, it was still a very smart looking bird and is captured superbly in the images below kindly submitted to Cornwall Birding by Andrew Jordan.
References: Finches and Sparrows - Clement, Harris and Davis (Helm Publishing 1999). Advanced Birding – Kenn Kaufman (Peterson Field Guides 1990)