How do I restore missing app icons for [free] purchased apps?

After rearranging the app icons on my iPad Air, several purchased [free] apps are no longer visible. I can access them via the App Store, which says they are downloaded, but the icons no longer appear on my home screen.

I've seen several discussion threads along these lines which refer to resetting user restrictions, etc - this does not apply here as there have never been any restritcions set on my iPad.

How do I restore these missing icons?

(Just FYI, the missing app icons are for Paper (by FiftyThree), BBC Weather and Dropbox.)