Looking at the power of backbenchers in Parliament, this article provides an excellent balance. Firstly, the motion was put forward by the Backbench Business Committee, was debated and voted on in Parliament and was supported by a majority of MPs. There were also some prominent MPs present, including the chair of the Defence Select Committee and the Shadow Defence Minister which speaks to some level of importance in the debate.
But, and it is a rather large but, there were only 40 MPs present at the debate. So whilst a majority, 37, of them voted for the motion, this hardly represents an overwhelming message to David Cameron. Equally, the vote itself is not binding on the Government and therefore no action is required in the aftermath of this vote. All of this rather suggests a lack of power on the backbenches.
This could also be used as an example for factions within parties as Tories those who did attend rather hoped to pressure Cameron into this spending commitment; not quite another backbench rebellion for Cameron, more of a gentle nudge.