The unaired pilot was 30 minutes shorter than the first episode that aired in 2010 and featured a different director, but Gatiss, who also stars in the hit BBC show, insists it was only scrapped because executives wanted to increase the run time.
Gatiss and fellow creator Steven Moffat ended up placing the unseen pilot on the series one DVD to end persistent rumours that it was axed because it was of poor quality.
Speaking on BBC Four series Mark Lawson Talks To, he explains: "The pilot is very good. We would have been very happy (to air it)... We knew we couldn't just bolt on another half hour, so Steve rewrote it and we remade it with a different director.
"Because of an internal decision to make it in another format, this gossip got out. I remember thinking, 'If we don't show people that it wasn't a disaster, this will live with us forever.'
"The argument is that you preserve the final version, sacrosanct, but I thought that was an insult to the original director and the production. The second one is more stylish, but it's a different beast."
A third series featuring Benedict Cumberbatch and Martin Freeman is expected next year, DESPITE the video below...