Winning with K+ Q v K+R
This ending is harder than generally realised. Ending textbooks usually mention the Philidor position, and state that the stronger side (White) can win by driving Black to the edge of the board, but underestimate Black's defensive resources.
The difficulties of the ending began to be acknowledged in 1978, following the exhibition match of the late GM Walter Browne versus BELLE chess computer. To general surprise, Browne could only draw first time round, winning the rematch - the game is also posted as my comment t0 GM Browne's chess.com orbituary. My notes on both games can be found here
I intend to add to this post when time allows with further links explaining how to win Q vs R systematically.