I'm the One the Daily Mail Warned You About

Possibly the best theory yet, courtesy of Private Eye.

When Sherlock Holmes appeared to leap off a tall building to his death, he was actually caught in mid air by an invisible Dr Who who tool him into the Tardis and sent him back in time o the point where he met Molly, who was actually protecting Sherlock from the Daleks who wanted to exterminate him using Moriarty, aka The Master, who had disguised himself as none other than Dr Watson before travelling forward in time to meet Sherlock when he appeared at his own funeral, thus allowing Sherlock to expose his brother Mycroft and reveal that he is Sir Arthur Conan Doyle who…