What type of bird is this?,bad pic included!

[robbocop33]

Was out with my Panasonic Lumix zoom camera and saw a bird in the distance along a burn,before I could focus etc it was off,but,i unintentionally snapped another bird out of focus while I half heartedly pressed the shutter.didn't even notice it in pic at first as what I was after 'should'have been at the top half of the pic,what a really yellow tail it has!(bottom right of pic)

[robbocop33]

It's funny,the bird i was actually after that flew away i thought was a pied wagtail.This one i photographed the tail is a really intense yellow.Thanks for that though!