How to fit a mantel shelf? Help?!!!

[PavlovtheForgetfulCat]

A solid wooden mantel shelf for above the fire place.

It has already attached to it, one metal plate either side, with a 'hook' facing downwards. And given to us were screws, plus a triangular fitting with one hole, then two holes.

How do we fit this? . We are thinking the 'hook' sits on the triangle somehow but we are stumped...

Probably the triangle gets screwed into the wall with the wider side up and the hook on the shelf clips into that iyswim?

That is what we thought - BUT, the screws do not sit flush that way iyswim. They stick out, so to get in the way of hooking, its not flush against the wall. We thought maybe the other way, with the narrower at the top, unscrewed, and the bottom 2 holes screwed in, so that the top has room to bend a smidge and allow it to fit on. Then the screws sit flush. But, that does not really make sense either, as the narrower top is rounded.

DH has put it up this way for now, and it is actually very secure. But possibly wrong . I might have to call the man I bought him from and ask him how it is done for sure.

And now I have pencil marks all over my lovely freshly painted white chimney breast...