How can I get the default theme from Windows 8 in my upgraded 8.1?

I upgraded to Windows 8.1, and it comes with a theme installed that I don't like. I loved the blue background/white flower theme that came installed on Windows 8 originally, but it seems to have vanished.

I've browsed through the windows.old folder but I don't see anything in there to recover it.

Is there a way to get this back?

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