I've heard the Willie Wagtails chittering away and sounding off in one of our sheds, and they've been very pro-active in harassing all the big birds in the area, so I figured they were nesting somewhere nearby. Yesterday I saw that they had started building on an old trailer cover in the shed. I thought this was a precarious sort of place to build, but (edit: I just realised that what they've actually built on is a flattish chunk of metal hanging off the skinny pipe, rather than the pipe itself.) It's also really quite exposed where it is, as butcherbirds and crows are quite fond of the shed as well. *frets* 
I get the feeling he'd like to tell me off, but can't with his mouth full. 
That is very intersting, I wonder what the outcome will be? Keep us posted. Love the photos
M-L
I will... it's the oddest thing, I mean, there are far better sheltered / protected spots in our other sheds (we have a few) that they might have chosen instead, within a few metres. It seems like this couple have a thing for precarious nesting spots.
Where they were nesting last year now has a Fairy Martin burrow/nest right next door to it, so I can understand why they might not want to return there. I wonder if anyone's done any research into how birds choose their nest spots? (I mean, I understand their birdy version of Maslow's hierarchy of needs, but specific positions).