Doctor Who: 13 Cool Details Steven Moffat Just Revealed About The Girl In The Fireplace
8. The Doctor Whipping Off His Glasses Was David Tennant's Idea
After quickly meeting child Reinette, the Doctor leaves, taking a clockwork droid with him. A few minutes later, he steps back through the "magic door" and discovers that many years have passed, and Reinette is now an attractive young woman.
Upon seeing her, he becomes a tiny bit flustered, clearly in awe of her beauty. He then quickly whips off his glasses, and according to Moffat, this small move was entirely David Tennant's idea. Make of that what you will.