BEAUTIFUL BRIGHT YELLOW BIRD ??? I/D PLEASE

Today there was a most beautiful bright yellow bird, slim and larger and longer than a sparrow.  It was plain bright yellow on the underside with no other markings, but on top, including the back of the head it was brown striped like the markings on a sparrow.  I have searched on Google and the RSPB identifier but cannot match it.  It was definitely not a wagtail - too small and it had a short tail.  It was not a siskin.  Can anyone help please?

Also, there is a blackbird nest in my gutter with the female incubating eggs.  I am hoping against hope that it does not rain because the gutter slopes down towards the nest.  With the sorry state of my dry garden, I cant believe I am praying it does not rain. 

Frogs, followed by toads have successfully laid spawn in my pond.  The frog tadpoles have hatched and are a teeming mass.  In spite of the fact that I am on a water meter, I am keeping the pond level topped up since the strong winds are evaporating the water!!