The Harry Potter star plays one of the little people in the New Wimbledon Theatre production, which features Priscilla Presley as the Wicked Queen.
Peter Bonner, who portrays a dwarf named Cheeky, contracted a ""chesty cold"" and was unable to appear, but no understudy had been cast, so the show went on as scheduled - with only six dwarves.
Davis tells Britain's Evening Standard newspaper, ""It is quite tricky, you have to re-work the scenes a little bit. I acknowledged it in the scene, I said 'We're one short' and another dwarf said 'We're all short' so I had to explain that he had gone to the doctor's because 'He's got what you've got Sneezy'. I just made a bit of a joke out of it.
""I put an announcement out just before the show, these things always happen last minute. It's not normally expected that one of the seven is going to be off so we don't have an understudy. We would have to have another short extra on constant standby.""
Bonner is now back onstage after overcoming his illness.