Impossible jigsaw?

I usually have a jigsaw on the go, to fill those idle moments (idle moments, what idle moments???).
I do like a difficult one, that takes weeks to finish, and I think this is one of the most challenging ones I have done.

It is the 'Impossible' sunflowers design, and has taken me since Christmas to complete.  So now I shall leave it to be admired for a few days, then break it up and on to the next one!