On the Twelfth Day of Corrie Christmas, my true love gave to me...
...12 Original Episodes
According to the website TV.com, Coronation Street was initially commissioned for only 12 episodes. As many of you know, the first episode of Coronation Street was broadcast in 1960. The show struck a chord with viewers and has been running ever since. According to coronationstreet.wikia.com, "since 9th December 1960, up to and including the episode transmitted on 12th December 2012, there have been 8015 episodes of Coronation Street..."
You can find out more at: http://coronationstreet.wikia.com/wiki/Coronation_Street_episodes
Phew! So there you have the 12 Days of Corrie Christmas.