Doctor Who: 12 Cool Details Revealed In Steven Moffat's Blink Commentary
2. Moffat Couldn't Think Of A Way To Defeat The Angels
In the end, the Angels are beaten when the TARDIS disappears while they're circling it, causing them to look into each other's eyes, locking them in place forever.
At face value, this seems like quite an obvious way to bring the Angels' reign of terror to an end - their one weakness is being observed by another living being, after all - but apparently, it wasn't so easy to come up with during the writing process.
In fact, trying to think up this resolution nearly "killed" Moffat. While discussing the scene, the writer mentioned that he struggled to find a way to defeat the Angels without the Doctor being there, and it proved such a tough story point to crack that he even had to consult fellow Who writer Mark Gatiss and ask for help.
Eventually, Moffat realised that his script notes made a point of there only being four Angels in the episode, and this led him to remember the "Angels stood around the four walls of the TARDIS" idea, something that he'd previously thought of, but had since forgotten.