I renewed my UK passport last year because the one I had ran out of pages. Had to submit the old passport (the one run out of pages) when I made application.
The old passport came back with the top right corner been snipped. Presumably, its been cancelled on the computer system?.
Now, I cannot seem to find the old (snipped right corner) passport. Do I need to report it? If it's cancelled already, I don't see the point. It being cancelling is also clearly visually apparent (snipped right corner)