The King's speech.

Reasons why the King's speech was so successful at selling out at the box-office night by night :

1. Its a conservative film.
2. The King’s Speech’ shows simple human goodness and the triumph of individual perseverance in the face of the most terrible adversity.
3. A powerful reminder of the sense of national duty and service that the core of the British royal family has remained wedded to for generations.

I found that the King's speech was so successful at the box-office as it was described as a  "unqualified must see".
Some critics viewed it as "powerful, hilarious and deeply moving story, told against the backdrop of a critical juncture in modern history".